Newly diagnosed epilepsy in children: presentation at diagnosis

Pathophysiology and definitions of seizures and status epilepticus

The pathophysiology of seizures is multifactorial and incompletely understood. Experimental work demonstrates that prolonged, abnormal, and excessive neuronal electrical activity in itself is injurious through several mechanisms independent of systemic acidosis and hypoxia. Population survival studies and laboratory investigations support the idea that brain injury and epileptogenesis result from status epilepticus. The basic distinction in seizure types is that of generalized and partial seizures. Correct classification of seizure types will aid in clinical communications and guide correct therapies. Revised definitions of generalized convulsive status epilepticus suggest making this diagnosis with as few as 5 minutes of continuous seizure activity.

Design considerations for a multicenter randomized controlled trial of early surgery for mesial temporal lobe epilepsy

PURPOSE

To describe the trial design for the multicenter Early Randomized Surgical Epilepsy Trial (ERSET). Patients with pharmacoresistant epilepsy are generally referred for surgical treatment an average of two decades after onset of seizures, often too late to avoid irreversible disability. ERSET was designed to assess the safety and efficacy of early surgical intervention compared to continued pharmacotherapy.

METHODS

ERSET is a randomized controlled, parallel group clinical trial with blinded outcome adjudication. Participants are patients with mesial temporal lobe epilepsy (MTLE) older than the age of 12 who have had pharmacoresistant seizures for not >2 years and are determined by detailed evaluation to be surgical candidates prior to randomization. The primary outcome measure is seizure freedom in the second year of a 2-year follow-up period. Health-related quality of life (HRQOL), neurocognitive function, ancillary outcomes, and adverse events were also measured.

RESULTS

Significant methodologic problems addressed by the study design included the following: recruitment of participants early in the course of epilepsy; establishment of operational definitions for "pharmacoresistant" and "early"; and standardization of diagnostic testing, medical treatment, and surgical interventions across multiple centers.

DISCUSSION

Rigorous trial designs to assess surgical interventions in epilepsy are necessary to provide evidence to guide treatment. This article is the first of a series; trial results will be reported in subsequent publications.

Management challenges in children with both epilepsy and intellectual disability

People who have both epilepsy and intellectual disability have significant problems requiring skilled health care management. Clinical nurse specialists have the unique opportunity to work with these people and their families to help them develop self-management and family management skills. In this article, we describe some factors associated with intellectual disability and epilepsy. In addition, we address the management challenges associated with this dual diagnoses in 3 areas: (1) problems associated with the management of seizure and prescription management, (2) problems associated with the seizure management other than prescriptions, and (3) life management issues. Finally, we suggest ways that clinical nurse specialists can foster development of management skills.

Cognitive outcomes in children who present with a first unprovoked seizure

PURPOSE

To determine the long-term cognitive and educational outcomes in children prospectively identified at the time of a first unprovoked seizure.

METHODS

A cohort of children with a first unprovoked seizure was enrolled and followed for a mean of 15 years. Cognitive function and educational outcomes were determined 10 or more years after the first seizure via standardized neuropsychological tests, school records, and structured interviews. Children with symptomatic etiology were excluded from the analysis. When available, siblings of study subjects were recruited as normal controls. Primary educational outcome was defined as enrollment into special education services or grade repetition.

RESULTS

Twenty-eight percent of (43 of 153) of children with a single seizure and 40% (42 of 105) of children with epilepsy received special education service or repeated a grade (p = 0.05). There was a statistically significant trend in which the children with more seizures tended to require special education or repeat a grade more often (28% in single seizure group vs. 34% in 2-9 seizure group vs. 64% in ≥10 seizure group; p = 0.004). Of 163 subjects who completed neuropsychological testing, children with single seizures tended to score higher than children with epilepsy on Wide Range Achievement Test-3 (WRAT) reading (p = 0.08), Test of Non-Verbal Intelligence-II (TONI-II) (p = 0.02), and Wechsler Intelligence Scale for Children (WISC)/Wechsler Adult Intelligence Scale (WAIS) (p = 0.07). There was no statistically significant difference between children with a single seizure and sibling controls.

CONCLUSION

The results suggest that children with a single seizure represent a group that is distinctly different from children with epilepsy and are more similar to sibling controls. In contrast, even children with very mild epilepsy have significantly worse educational outcomes.

Differences in child versus parent reports of the child's health-related quality of life in children with epilepsy and healthy siblings

OBJECTIVES

Self versus proxy perspectives may produce different results that are important for clinical decision-making and for assessing outcomes in research studies. We examined differences in child versus parent report of the child's health-related quality of life (HRQOL) in a large prospective, community-based study of newly diagnosed childhood epilepsy that included children with epilepsy (case) and sibling controls.

METHODS

HRQOL was assessed 8 to 9 years after initial diagnosis of epilepsy in a subset of 143 case-control matched pairs using the Child Health Questionnaire (CHQ), a generic HRQOL measure with child (CHQ-CF87), and parent (CHQ-PF50) versions.

RESULTS

There were no significant differences between self-reported case and sibling control HRQOL scores on 9 of 11 scales or 2 global items. Nevertheless, parent ratings were significantly better (higher HRQOL) for sibling controls compared with epilepsy cases on 10 of 12 scales, global behavior and general health items, and the physical and psychosocial summary scores (P≤0.05). Parent-child agreement was low for cases and controls (kappa 0.27-0.33) for three single-item questions with the same wording on parent and child versions. Parent ratings of the case's HRQOL were often significantly associated with 5-year remission status and current antiepileptic drug use, but the case's self-reported HRQOL scores were not. In contrast, current pharmacoresistance was often associated with the child and parent ratings of the child's HRQOL.

CONCLUSION

Children with epilepsy report HRQOL that is comparable to that of sibling controls, while parents rate children with epilepsy as having lower HRQOL than sibling controls. Measuring outcomes in studies of this population should incorporate both perspectives.

Parental report of behavioral and cognitive diagnoses in childhood-onset epilepsy: A case-sibling-controlled analysis

Evidence from multiple sources has highlighted the increased burden of cognitive, behavioral, and psychiatric disorders in childhood-onset epilepsy. Some of this increased morbidity, however, is attributable to underlying structural and metabolic insults. We assessed whether cognitive/behavioral/psychiatric disorders are associated with epilepsy of unknown or presumed genetic cause in young people with epilepsy (cases) compared with sibling controls. Our analyses included 217 cases who were enrolled in the Connecticut Study of Epilepsy between 1993 and 1997 and 217 sibling controls. Information was collected from a parent interview conducted 8-9years after the case was diagnosed with epilepsy. Relative to controls, parents were more likely to report that their case children were slow learners (OR=4.6, P<0.001), had a language disorder (OR=5.8, P<0.001), and had engaged in self-injurious behaviors other than suicide attempts (OR=5.5, P=0.013). Future research should examine whether these conditions first present during childhood influence prognosis into adulthood.

Course and outcome of childhood epilepsy: a 15-year follow-up of the Dutch Study of Epilepsy in Childhood

PURPOSE

To study the course and outcome of childhood-onset epilepsy during 15-year follow-up (FU).

METHODS

We extended FU in 413 of 494 children with new-onset epilepsy recruited in a previously described prospective hospital-based study by questionnaire.

RESULTS

Mean FU was 14.8 years (range 11.6-17.5 years). Five-year terminal remission (TR) was reached by 71% of the cohort. Course during FU was favorable in 50%, improving in 29%, and poor or deteriorating in 16%. Mean duration of seizure activity was 6.0 years (range 0-21.5 years), strongly depending on etiology and epilepsy type. Duration was <1 year in 25% of the cohort and exceeded 12 years in another 25%. Antiepileptic drugs (AEDs) were used by 86% during a mean of 7.4 years: one-third had their last seizure within 1 year of treatment, and one-third continued treatment at the end, although some had a 5-year TR. At last contact, 9% of the cohort was intractable. In multivariate analysis, predictors were nonidiopathic etiology, febrile seizures, no 3-month remission, and early intractability. Eighteen patients died; 17 had remote symptomatic etiology. Standardized mortality ratio for remote symptomatic etiology was 31.6 [95% confidence interval (CI) 18.4-50.6], versus 0.8 [95% CI 0.02-4.2] for idiopathic/cryptogenic etiology.

DISCUSSION

In most children with newly diagnosed epilepsy, the long-term prognosis of epilepsy is favorable, and in particular, patients with idiopathic etiology will eventually reach remission. In contrast, epilepsy remains active in approximately 30% and becomes intractable in approximately 10%. AEDs probably do not influence epilepsy course; they merely suppress seizures. Mortality is significantly higher only in those with remote symptomatic etiology.

Recurrence risk after withdrawal of antiepileptic drugs in children with epilepsy: a prospective study

AIM

To study recurrence risk after withdrawal of antiepileptic drugs in children with epilepsy.

METHODS

All children younger than 14 with two or more unprovoked seizures 24h apart who were seen at our Hospital between 1994 and 2004 were included consecutively and prospectively followed. Patients previously examined in other centres were excluded. All patients who entered a remission were proposed to stop medication and were followed.

RESULTS

Three hundred and fifty three children with two or more unprovoked seizures were attended. A total of 238 entered a remission period and were proposed to stop medication, 216 accept. Mean seizure-free time before medication withdrawal was 2.2 years. Kaplan-Meier estimate of recurrence risk was 23% at 2 years (95% CI: 17-29) and 28% at 5 years (95% CI: 22-34). A remote symptomatic etiology, various seizure types and a history of prior febrile seizures or prior neonatal seizures were associated with a significant increase in recurrence risk in univariable and multivariable analyses using Cox proportional hazards model. Recurrence risk at 2 years was 17% (95% CI: 11-23) for idiopathic/cryptogenic epilepsies and 41% (85% CI: 28-54) for remote symptomatic epilepsies. Recurrence risks at 2 years by epileptic syndrome were West syndrome (0%), benign rolandic epilepsy (10%), epilepsy without unequivocal partial or generalized seizures (11%), benign infantile seizures (13%), absence epilepsy (16%), cryptogenic partial epilepsies (20%), symptomatic partial epilepsies (45%), symptomatic generalized epilepsies (54%).

CONCLUSIONS

Recurrence risk after withdrawal of antiepileptic treatment in children is low. Etiology and syndromic diagnosis are the main predictive factors.

New-onset afebrile seizures in infants: role of neuroimaging

OBJECTIVE

To investigate the presenting characteristics of new-onset afebrile seizures in infants (age 1-24 months) and the yield of neuroimaging.

METHODS

Prospective data were obtained from a standardized evaluation and management plan mandated by a critical care pathway. A total of 317 infants presented with new-onset afebrile seizures between 2001 and 2007. EEG was performed on 90.3%, head CT was obtained on 94%, and MRI was obtained on 57.4%.

RESULTS

We found half of the infants had partial features to their seizures, yet evidence for primary generalized seizures was rare. The majority had more than 1 seizure upon presentation. Seizures in this age group tended to be brief, with 44% lasting less than 1 minute. EEG abnormalities were found in half. One-third of CTs were abnormal, with 9% of all CTs requiring acute medical management. Over half of MRIs were abnormal, with cerebral dysgenesis being the most common abnormality (p < 0.05). One-third of normal CTs had a subsequent abnormal MRI-only 1 resulted in altered medical management.

CONCLUSIONS

Infantile seizures are usually brief, but commonly recurrent, and strong consideration should be made for inpatient observation. Acute imaging with CT can alter management in a small but important number of infants. Due to the superior yield, strong consideration for MRI should be given for all infants, as primary generalized seizures are rare, and there is a high rate of cerebral dysgenesis.

Idiopathic childhood occipital epilepsy of Gastaut: a review and differentiation from migraine and other epilepsies

The purpose of this review is to provide guidance for appropriate diagnosis and management of idiopathic childhood occipital epilepsy of Gastaut. The typical clinical features are visual seizures that typically consist of brief elementary visual hallucinations, which are mainly multicolored and circular. Ictal blindness and deviation of the eyes are also common symptoms. The seizures are usually frequent and diurnal. The electroencephalography is the only investigation with abnormal results, showing occipital spikes and often occipital paroxysms demonstrating fixation-off sensitivity. Brain magnetic resonance imaging is used to exclude symptomatic occipital epilepsy. Patients usually respond well to antiepileptic medication and about two-thirds remit by the age of 16 years. Idiopathic childhood occipital epilepsy of Gastaut is frequently misdiagnosed as migraine with visual aura, acephalgic, or basilar migraine. Differentiation from symptomatic occipital epilepsy, particularly when children are otherwise normal, can be difficult. Most children need prophylactic antiepileptic medication.

Identification of pharmacoresistant epilepsy

There is no single definition of pharmacoresistant (intractable, refractory) epilepsy. Prospective identification of pharmacoresistance is complicated by the variability of its appearance across different types of epilepsy and the variability of seizure control within a given patient over time. Failure of informative trials of two appropriate antiepileptic drugs has been recommended as a threshold that should trigger referral for evaluation at a comprehensive epilepsy center. Maximizing seizure control is imperative for reducing the risks and consequences of epilepsy, including the cognitive and psychiatric comorbidities and even sudden death.

Neuropsychological status at seizure onset in children: risk factors for early cognitive deficits

OBJECTIVE

This large, prospective, community-based study characterized neuropsychological functioning and academic achievement at the time of the first recognized seizure and identified risk factors for cognitive deficits.

METHODS

We compared 282 children (ages 6-14 years, IQ > or =70) with a first recognized seizure to 147 healthy siblings on a battery of well-standardized and widely used neuropsychological and academic achievement tests and examined relationships with demographic and clinical variables.

RESULTS

In this intellectually normal cohort, 27% with just one seizure and up to 40% of those with risk factors exhibited neuropsychological deficits at or near onset. Risk factors associated with neuropsychological deficits included multiple seizures (i.e., second unprovoked seizure; odds ratio [OR] = 1.96), use of antiepileptic drugs (OR = 2.27), symptomatic/cryptogenic etiology (OR = 2.15), and epileptiform activity on the initial EEG (OR = 1.90); a child with all 4 risks is 3.00 times more likely than healthy siblings to experience neuropsychological deficits by the first clinic visit. Absence epilepsy carried increased odds for neuropsychological impairment (OR = 2.00).

CONCLUSIONS

A subgroup of intellectually normal children with seizures showed neuropsychological deficits at onset. Academic achievement was unaffected, suggesting that there is a window early in the disorder for intervention to ameliorate the impact on school performance. Therefore, the risk factors identified here (especially if multiple risks are present) warrant swift referral for neuropsychological evaluation early in the course of the condition.

Response to sequential treatment schedules in childhood epilepsy: risk for development of refractory epilepsy

PURPOSE

To investigate response to sequential treatment schedules and risk of development of refractory epilepsy in childhood.

METHODS

All children younger than 14 years with two or more unprovoked seizures seen at our hospital between 1994 and 2004 were included and prospectively followed. "Seizure control" was defined as a 2-year seizure-free interval without further recurrences except those related to attempts of medication withdrawal and "refractory epilepsy" as failure of >2 drugs plus >1 seizure/month for > or =18 months.

RESULTS

343 Patients were included, 191 males and 152 females. Mean age at diagnosis was 4y 10 mo (SD 3 year 10 month). Mean follow-up period was 76.2 mo (SD 35.2). The probability of achieving "seizure control" was 70% and 86% at 5 and 10 years. 59% of patients were "controlled" with the first drug used. Among patients failing the first, second and third therapeutic regimen due to lack of efficacy, 39%, 23% and 12% respectively were finally "controlled" with subsequent treatment schedules Risk of development of refractory epilepsy was 8% and 12% at 6 and 10 years.

CONCLUSION

After failing a first drug, a significant proportion of children can still be controlled with subsequent therapeutic schedules. Only a small proportion develops refractory epilepsy.

Frequency, prognosis and surgical treatment of structural abnormalities seen with magnetic resonance imaging in childhood epilepsy

The epidemiology of lesions identified by magnetic resonance imaging (MRI), along with the use of pre-surgical evaluations and surgery in childhood-onset epilepsy patients has not previously been described. In a prospectively identified community-based cohort of children enrolled from 1993 to 1997, we examined (i) the frequency of lesions identified by MRI; (ii) clinical factors associated with 'positive' MRI scans; and (iii) the utilization of comprehensive epilepsy evaluations and neurosurgery. Of the original cohort of 613 children, 518 (85%) had usable MRI scans. Eighty-two (16%) had MRI abnormalities potentially relevant to epilepsy ('positive' scans). Idiopathic epilepsy syndromes were identified in 162 (31%) of whom 3% had positive scans. The remainder had non-idiopathic epilepsy syndromes of which 22% had positive MRI findings. Multiple logistic regression analysis identified non-idiopathic epilepsy and abnormal motor-sensory (neurological) examinations as predictors of a positive MRI scan. Of the non-idiopathic patients with normal neurological exams and who were not pharmacoresistant, 10% had positive MRI scans, including four patients with gliomas. Evaluations at comprehensive epilepsy centres occurred in 54 pharmacoresistant cases. To date 5% of the imaged cohort or 8% of non-idiopathic epilepsy patients have undergone surgical procedures (including vagal nerve stimulator implantation) to treat their epilepsy (n = 22) or for tumours (n = 6) without being drug resistant. Applying our findings to the general population of children in the USA, we estimate that there will be 127/1 000 000 new cases per year of pharmacoresistant epilepsy, and 52/1 000 000 childhood-onset epilepsy patients undergoing epilepsy evaluations. In addition, approximately 27/1 000 000 will have an epilepsy-related surgical procedure. These findings support recommendations for the use of MRI in evaluating newly diagnosed paediatric epilepsy patients, especially with non-idiopathic syndromes, and provide estimates on the utilization of comprehensive evaluations and surgery.

Remission of epilepsy after two drug failures in children: a prospective study

OBJECTIVE

Determine the probability of a more than 1-year remission after failure of a second drug in children prospectively followed from initial diagnosis of epilepsy and then from time of second drug failure. Identify prognostic factors for remission after second drug failure.

METHODS

Of 613 children, 128 did not respond favorably to 2 drugs, had a trial of at least a third drug (median, 3), and were followed for more than 1 year (median, 10.1 years) since second drug failure. Product limit and proportional hazards techniques were used to analyze predictors of any 1-year remission (Rem1) and 1- and 3-year remission at last contact (Rem1/3-LC).

RESULTS

Seventy-three patients (57%) had a remission. Repeated remissions and relapses were common. Only 48 (37.5%) achieved Rem1-LC and 28 (23%) Rem3-LC. Idiopathic epilepsy (Rem1: rate ratio [RR], 3.64, p < 0.0001; Rem1-LC: RR, 2.57, p = 0.008) and seizure frequency (Rem1: RR, 0.76, p = 0.003; Rem1-LC: RR, 0.82, p = 0.04 per increase in category) were the most robust predictors. Symptomatic cause was the only correlate of Rem3-LC. Remission before second drug failure did not predict remission after second drug failure.

INTERPRETATION

Remission after second drug failure is common but often temporary. Children who have not responded to two appropriate drugs should be carefully evaluated to maximize therapy and possibly considered for more aggressive treatments.

Magnetic resonance imaging findings in children with a first recognized seizure

This study characterized structural abnormalities associated with onset of seizures in children, using magnetic resonance imaging and a standardized classification system in a large prospective cohort. Two hundred eighty-one children aged 6-14 years completed magnetic resonance imaging within 6 months of their first recognized seizure. Most examinations were performed with a standardized, dedicated seizure protocol; all were scored using a standard scoring system. At least one magnetic resonance imaging abnormality was identified in 87 of 281 (31%) children with a first recognized seizure. Two or more abnormalities were identified in 34 (12%). The commonest abnormalities were ventricular enlargement (51%), leukomalacia/gliosis (23%), gray-matter lesions such as heterotopias and cortical dysplasia (12%), volume loss (12%), other white-matter lesions (9%), and encephalomalacia (6%). Abnormalities defined as significant, or potentially related to seizures, occurred in 40 (14%). Temporal lobe and hippocampal abnormalities were detected at a higher frequency than in previous studies (13/87). Magnetic resonance imaging and a standardized, reliable, valid scoring system demonstrated a higher rate of abnormal findings than previously reported, including findings formerly considered incidental. Practice parameters may need revision, to expand the definition of significant abnormalities and support wider use of magnetic resonance imaging in children with newly diagnosed seizures.

Residual cognitive effects of uncomplicated idiopathic and cryptogenic epilepsy

We assessed residual cognitive deficits in young people with idiopathic and cryptogenic epilepsy. In the setting of an ongoing prospective study, we invited participants initially diagnosed and enrolled in the cohort 8-9 years earlier to undergo standardized neuropsychological assessment. Sibling controls were invited when available. We analyzed 143 pairs in which cases had idiopathic or cryptogenic epilepsy and both case and control had normal intelligence. Compared with that for siblings, the Full Scale IQ for cases was 3.3 points lower (P=0.01) mainly due to slower processing speed, which was 5.6 points lower (P=0.0004). Word reading (P=0.04) and spelling (P=0.01), but not other scores, were also lower in cases. Remission status and drug use did not influence findings. In young people of normal intelligence with idiopathic or cryptogenic childhood-onset epilepsy, substantial residual effects of epilepsy appear to be confined largely to slower processing speed.

Assessing severity of epilepsy in children: preliminary evidence of validity and reliability of a single-item scale

The development and initial validity and reliability testing of a single-item, 7-point global rating scale designed for neurologists to assess the overall severity of epilepsy in children, the Global Assessment of Severity of Epilepsy (GASE) Scale, is described. The GASE Scale was quick and easy to use. Median epilepsy severity in the development sample was 3 (moderately severe), with a range from 1 ("not severe at all") in 36 patients (26.9%) to 7 ("extremely severe") in 7 patients (5.2%). Preliminary evidence of construct validity was found in support for our a priori predictions of associations between GASE scores and neurologists' ratings of seven individual clinical aspects of epilepsy and in a cumulative R(2) for the GASE score of 81% using ratings of the clinical aspects of epilepsy. Weighted kappa was 0.85 (95% CI: 0.79, 0.90) for inter-rater reliability and 0.90 (95% CI: 0.82, 0.98) and 0.95 (95% CI: 0.91, 0.98) for test-retest reliability for each of two raters. These promising initial results support continuation of the multistage process of testing the validity and reliability of the GASE Scale within various clinical contexts.

Incidence of epilepsies and epileptic syndromes among children in Navarre, Spain: 2002 through 2005

All incident cases of children living in Navarre, Spain, younger than 15 years of age with newly diagnosed epilepsy (2002-2005) were registered in a prospective study, with epidemiologic and clinical data and complementary study results collected. Based on International League Against Epilepsy criteria, 191 patients were diagnosed as having epilepsy. The overall incidence rate is 62.6 cases per 100 000, with the highest incidence (95.3 cases per 100 000) during the first year of life. Fifty-five percent of patients have focal epilepsies, 42.9% generalized epilepsies, and 2.1% undetermined epilepsies. Among infants, West syndrome (45.5%), epilepsies associated with specific syndromes (27.3%), and focal symptomatic epilepsies (13.6%) are the most prevalent syndromes. In early childhood, the main syndromes are focal symptomatic (22.7%) and cryptogenic (21.2%) epilepsies and Doose syndrome (13.6%). Among school-aged children, focal benign epilepsies (27.8%) and cryptogenic and absence epilepsies (18.5% for both) are the most prevalent, with focal cryptogenic epilepsies (26.5%) and benign epilepsies (18.4%) most prevalent among adolescents.

Multi-site voxel-based morphometry: methods and a feasibility demonstration with childhood absence epilepsy

AIM

Voxel-based morphometry analysis of neurological disorders would benefit if it could use data acquired from different scanners, but scanner based contrast variation could interfere with the detection of disease-specific structural abnormalities. In this study we examine MRI data from three different sites to investigate structural differences between childhood absence epilepsy (CAE) subjects and controls.

METHODS

T1-weighted structural MRI scans were acquired from: Site A. 10 CAE, 213 controls; Site B. 15 CAE, 33 controls; and Site C. 19 CAE, 11 controls. The images were processed using the optimised VBM protocol. Three statistical analyses were undertaken: (1) Comparisons of CAE subjects and controls stratified by site. (2) Between-site comparison of controls from each site. (3) Factorial analysis of all data with site and disease status as factors.

RESULTS

Consistent regions of structural change, located in the thalamic nuclei, were observed in the within-site analysis of CAE vs controls. Analysis of control scans, however, indicated site-specific differences between controls, which required that we adjust for site in combined analyses. Analysis of all data with adjustment for site confirmed the finding of thalamic atrophy in CAE cases.

CONCLUSION

Combined VBM analysis of structural MRI scans acquired from different sites yield consistent patterns of structural change in CAE when site is included as a factor in the statistical analysis of the processed images. In MRI studies of diseases where only a limited number of subjects can be imaged at each site, our study supports the possibility of effective multi-site studies as long as both disease subjects and healthy controls are acquired from each site.

Role of brain inflammation in epileptogenesis

Inflammation is known to participate in the mediation of a growing number of acute and chronic neurological disorders. Even so, the involvement of inflammation in the pathogenesis of epilepsy and seizure-induced brain damage has only recently been appreciated. Inflammatory processes, including activation of microglia and astrocytes and production of proinflammatory cytokines and related molecules, have been described in human epilepsy patients as well as in experimental models of epilepsy. For many decades, a functional role for brain inflammation has been implied by the effective use of anti-inflammatory treatments, such as steroids, in treating intractable pediatric epilepsy of diverse causes. Conversely, common pediatric infectious or autoimmune diseases are often accompanied by seizures during the course of illness. In addition, genetic susceptibility to inflammation correlated with an increased risk of epilepsy. Mounting evidence thus supports the hypothesis that inflammation may contribute to epileptogenesis and cause neuronal injury in epilepsy. We provide an overview of the current knowledge that implicates brain inflammation as a common predisposing factor in epilepsy, particularly childhood epilepsy.

10-year research update review: psychiatric problems in children with epilepsy

OBJECTIVE

To critically review literature published from 1996 to 2007 on psychopathology in children with epilepsy (CWE).

METHOD

Using Ovid, we searched Medline and PsychInfo databases for original studies on epidemiology, risk factors, clinical characteristics, treatment, and outcome of psychopathology in CWE, ages 0 to 18 years, using the terms "psychopathology," "emotional and behavioral problems," and "mental health problems." We selectively present the findings of studies that are clinically relevant to mental health professionals.

RESULTS

Psychopathology occurs in 37% to 77% of CWE, and attention, internalizing, and thought problems may be specific to epilepsy. Cognitive and linguistic deficits, as well as family factors, have moderating effects on psychopathology in CWE. The association of epilepsy-related variables, including antiepileptic drugs, with psychopathology is inconsistent in cognitively normal CWE. Children with symptomatic epilepsy and devastating epilepsy syndromes have high rates of global developmental delay, hyperactivity, and autistic symptoms. The treatment of psychopathology in CWE integrates standard psychiatric practices.

CONCLUSIONS

Epilepsy is a neuropsychiatric disorder characterized by seizures, psychopathology, cognitive, and linguistic problems. Improved early identification of CWE at risk for psychopathology, evidence-based psychiatric treatment, and multidisciplinary management strategies would advance clinical practice in this highly complex field of pediatric neuropsychiatry.

High risk of reading disability and speech sound disorder in rolandic epilepsy families: case-control study

PURPOSE

Associations between rolandic epilepsy (RE) with reading disability (RD) and speech sound disorder (SSD) have not been tested in a controlled study. We conducted a case-control study to determine whether (1) RD and SSD odds are higher in RE probands than controls and (2) an RE proband predicts a family member with RD or SSD, hence suggesting a shared genetic etiology for RE, RD, and SSD.

METHODS

Unmatched case-control study with 55 stringently defined RE cases, 150 controls in the same age range lacking a primary brain disorder diagnosis, and their siblings and parents. Odds ratios (OR) were calculated by multiple logistic regression, adjusted for sex and age, and for relatives, also adjusted for comorbidity of RD and SSD in the proband.

RESULTS

RD was strongly associated with RE after adjustment for sex and age: OR 5.78 (95% CI: 2.86-11.69). An RE proband predicts RD in family members: OR 2.84 (95% CI: 1.38-5.84), but not independently of the RE proband's RD status: OR 1.30 (95% CI: 0.55-12.79). SSD was also comorbid with RE: adjusted OR 2.47 (95%CI: 1.22-4.97). An RE proband predicts SSD in relatives, even after controlling for sex, age and proband SSD comorbidity: OR 4.44 (95% CI: 1.93-10.22).

CONCLUSIONS

RE is strongly comorbid with RD and SSD. Both RD and SSD are likely to be genetically influenced and may contribute to the complex genetic etiology of the RE syndrome. Siblings of RE patients are at high risk of RD and SSD and both RE patients and their younger siblings should be screened early.

Incidencia de la epilepsia infantil

OBJECTIVE

To calculate the annual incidence rate of epilepsy, as well as the relative distribution of the different forms of epilepsy and epileptic syndromes in infants and children.

PATIENTS AND METHODS

All incident cases in infants and children aged less than 15 years living in Navarre (Spain) with newly diagnosed epilepsy (2002 to 2005) were prospectively registered. Epidemiological and clinical data and the results of complementary investigations were recorded. The criteria for epileptic seizures and epileptic syndromes of the International League Against Epilepsy (ILAE) and the ILAE guidelines for epidemiological studies were applied.

RESULTS

One hundred ninety-nine patients were diagnosed with childhood epilepsy (22 infants, 66 young children, 54 school children and 49 adolescents). The annual incidence rate was 62.6 cases per 100,000 (95 % CI: 62.3-62.9). The incidence rate was highest during the first year of life (95.3 per 100,000) and gradually decreased until adolescence (48.7/100,000). Focal epilepsy was found in 55 %, generalized epilepsy in 42.9 %, and undetermined epilepsy in 2.1 %. In infants, the most prevalent epileptic syndromes were West syndrome (45.5 %), epilepsies associated with specific syndromes (27.5 %), and focal symptomatic epileptic syndromes (13.6 %). In early childhood, the main syndromes were focal symptomatic epilepsy (22.7 %), cryptogenic epilepsy (21.2 %), and Doose syndrome (13.6 %). In schoolchildren, the most frequent syndromes were focal benign epilepsies (27.8 %), cryptogenic epilepsy (18.5 %), and absence epilepsy (18.5 %). In adolescents, the most frequent syndromes were focal cryptogenic epilepsies (27.6 %) and benign epilepsies (18.4 %).

CONCLUSIONS

The annual incidence rate of epilepsy in infants and children in Navarre is similar the rates described for other western countries, with the highest incidence rate being found during the first year of life and gradually diminishing until adolescence. Published data concerning the relative frequency of epilepsy and epileptic syndromes are discordant. These discrepancies highlight the difficulty of establishing a syndromic diagnosis in this age group and the need to apply uniform criteria in order to obtain valid and comparable epidemiological data.

Behavior and social competency in idiopathic and cryptogenic childhood epilepsy

Behavioral and related disorders are frequently reported in association with childhood epilepsy but the reasons for this are unclear. In a long-term prospective, community-based study of newly-diagnosed childhood epilepsy, behavioral assessments (Child Behavior Checklist) were performed in children 8 to 9 years after the initial diagnosis of epilepsy to determine the impact of remission and medication status on behavioral problems. Children with epilepsy were also compared with sibling controls. A total of 226 children (108 females, 118 males; mean age 13y 1mo [SD 2y 8mo], range 8-17y) with idiopathic or cryptogenic epilepsy were included in the analyses. One hundred and twenty-eight matched pairs were included in analyses of case-sibling differences. Lack of remission and current medication use were associated with worse behavioral problem and competency scores. Lack of remission generally had a greater effect than medication use, except for attention problems; medication status had the more deleterious effect (p<0.001). Children with epilepsy had significantly worse behavioral problems and competency scores relative to sibling controls. Even in paris in which the patient was seizure-free and off medication, significant case-sibling differences persisted for most scales (p=0.05 to p=0.001). Lack of remission and continued use of antiepileptic drugs have a negative influence on behavioral problems in children with epilepsy but do not fully explain the worse scores relative to siblings. This suggests an independent effect associated with the epilepsy itself.

Epilepsy in children in Navarre, Spain: epileptic seizure types and epileptic syndromes

Data for children 1 month to 15 years of age at the time of diagnosis of epilepsy were recorded from the children's hospital "Virgen del Camino" in Pamplona (Spain) from January to December 2005. International League Against Epilepsy criteria were used for diagnoses. A total of 365 children were recruited into the study. Mean age at diagnosis was 5.97 years, and time of follow-up was 4.6 years. Etiology was idiopathic in 166 (45.5%), cryptogenic in 106 (29.0%), and symptomatic in 93 (25.5%). Focal seizures were seen in 52.9% of the patients, generalized epilepsy in 43.5%, and 3.6% were not determined. In infants, West syndrome (34.1%) and focal symptomatic seizures (24.4%) were the most prevalent syndromes. In early childhood, the main syndromes were cryptogenic focal epilepsies (17.7%) and Doose syndrome (12.8%). In school-aged children, benign epilepsies (27.3%) and absences (24.5%) were prevalent. In adolescents, cryptogenic focal epilepsies (26.6%) and benign epilepsies (23.4%).

Vigabatrin

Refractory epilepsies such as infantile spasms (IS) and complex partial seizures (CPS) can have a severe negative impact on the neurological integrity and quality of life of affected patients, in addition to drastically increasing their risk of premature mortality. Early identification of potentially effective pharmacotherapy agents is important. Vigabatrin has been shown to be a generally well tolerated and effective antiepileptic drug (AED) in a wide variety of seizure types affecting both children and adults, particularly those with IS and CPS. A bilateral, concentric constriction of the peripheral visual field characterizes the visual field defect (VFD) associated with vigabatrin, well characterized by numerous studies. This peripheral VFD presents in 30-50% of patients with exposure of several years; however, most of these patients are asymptomatic. In well-controlled studies, the earliest onset in patients with CPS is 11 months and at 5 months in infants, with average onsets being more than 5 years and 1 year, respectively. Patients with a peripheral VFD retain an average 65 degrees of lateral vision (normal, 90 degrees). The fact that many patients never develop the vigabatrin-related peripheral VFD, despite long-term exposure at high doses, may support the hypothesis that the injury is an idiosyncratic adverse drug reaction (as opposed to a strict dose- or duration-dependent toxicity). Effective testing methods are available to aid in the early detection and management of the peripheral VFD. This article discusses issues of importance to clinical decision-making in the use of vigabatrin to assist the physician and patient in assessing the benefits of vigabatrin therapy and understanding the potential risks of the VFD and uncontrolled seizures.

Epilepsien im Jugendalter

Zusammenfassung: Der Beitrag stellt die Bedeutung chronischer Erkrankungen des Jugendalters im Hinblick auf die Interaktion mit allgemeinen normativen Entwicklungsaufgaben der Adoleszenz dar und spezifiziert dann die besonderen psychosozialen Charakteristika der Epilepsie als häufigste neurologische Erkrankung des Jugendalters. Die besondere Bedeutung der Compliance und Aspekte der Krankheitsbewältigung für Jugendliche mit Epilepsie werden im Hinblick auf wichtige entwicklungspsychologische Themen des Jugendalters diskutiert. Bedeutung und Ziele von Patientenschulung als zentraler Behandlungsbaustein bei chronischen Erkrankungen werden erläutert.

Epilepsias y síndromes epilépticos entre los alumnos de Educación Primaria (6-12 años)

OBJECTIVE

To analyze the epidemiological characteristics and proportional distribution of epilepsy and epileptic syndromes among primary school children.

PATIENTS AND METHODS

The medical records of all children diagnosed with epilepsy between the ages of 6 and 12 years who attended a follow-up visit in 2005 were retrospectively reviewed. The sample consisted of 169 patients (85 boys and 84 girls). Epidemiological and clinical characteristics and complementary investigations were collected. The criteria defined by the International League Against Epilepsy (ILAE) were used in the diagnosis.

RESULTS

The mean age at diagnosis was 8.8 years (95% CI: 0.2). The mean duration of follow-up was 3.5 years (95% CI: 0.32). Etiology was idiopathic in 102 patients (60.4%), cryptogenic in 36 (21.3%), and symptomatic in 31 (18.3%). A personal and/or familial history of febrile seizures was reported in 10.7% and familial epilepsy was found in 23.5%. Neuroimaging was performed in 162 patients (95.9%), and anomalies were detected in 33 (20.4%). In idiopathic epilepsies, generalized epilepsies were observed in 56.9% of the patients and focal seizure in 43.1%. Focal seizures were more frequent than generalized epilepsy in cryptogenic (63.9% versus 27.8%) and symptomatic forms (74.2 % versus 22.6%). The most prevalent syndromes were benign focal seizures (26.1%) and typical absence seizures (20.7%). Children with symptomatic epilepsies had a greater prevalence (p<0.05) of learning difficulties (66.7%) than those with cryptogenic (32.4%) or idiopathic forms (2.9%).

CONCLUSIONS

Most seizures in primary school children were idiopathic (benign focal seizures and/or typical absence seizures) and did not interfere with schooling. Cryptogenic and symptomatic epilepsies were less prevalent, but a high proportion of patients had substantial neurological and mental impairment or was refractory to antiepileptic drugs, giving rise to educational and psychological needs requiring specialized intervention.

Childhood epilepsy: failures along the path to diagnosis and treatment

Despite the importance of early diagnosis in childhood epilepsy, few published studies address the process of the child's entry into the health care system. The purpose of this article is to describe parental accounts of the diagnostic process and corresponding treatment for their children. We interviewed 21 parents of children who had both epilepsy and significant learning problems using semistructured open-ended interviews. During the interview, we asked parents to describe their child's medical history. Qualitative data analysis techniques were used to analyze the interviews. They revealed three system failures where the recognition and treatment of epilepsy fall short of an ideal diagnostic trajectory: (1) parents not seeking treatment for their child's epilepsy, (2) health care providers not recognizing seizures, and (3) health care providers not making accurate diagnoses or initiating inappropriate treatment. This study provides a foundation on which to build future studies.

Evaluation of first unprovoked seizures in children by general paediatricians in New Zealand

AIM

To determine current practice of general paediatricians in New Zealand in the investigation and management of a first unprovoked seizure in childhood.

METHODS

A self-administered questionnaire was emailed to 109 general paediatricians in New Zealand. The questionnaire presented the participant with three hypothetical case scenarios representing a generalised tonic clonic seizure, a complex partial seizure and an episode of non-specific collapse. The participant was asked to indicate what investigations and course of management was required.

RESULTS

Forty-seven questionnaires were returned. Primary investigations included an electroencephalogram (EEG) in 47% of cases after a first generalised tonic clonic seizure increasing to 89% after a second. Ninety-one per cent of paediatricians were likely to request an EEG after a complex partial seizure. No paediatrician would request neuroimaging following a first generalised tonic clonic seizure. Neuroimaging was requested by 10% of paediatricians following a second generalised tonic clonic seizure and by 47% following a complex partial seizure. No paediatrician elected to initiate antiepileptic drugs after a first generalised tonic clonic seizure, but 49% would initiate treatment after a second generalised tonic clonic seizure. Eleven per cent of paediatricians would start treatment after a single complex partial seizure.

CONCLUSION

Less than 50% of general paediatricians would request an EEG after a first unprovoked seizure. This is an unexpectedly low rate that may reflect accessibility. New Zealand paediatricians had an appropriately low rate of requesting neuroimaging. As currently recommended no general paediatricians began antiepileptic drugs in the scenario of a single uncomplicated seizure in the absence of other risk factors.

Epilepsy in North America: A Report Prepared under the Auspices of the Global Campaign against Epilepsy, the International Bureau for Epilepsy, the International League Against Epilepsy, and the World Health Organization

In North America, overall epilepsy incidence is approximately 50/100,000 per year, highest for children below five years of age, and the elderly. The best data suggest prevalence of 5-10/1000. Potential effects of gender, ethnicity, access to care and socioeconomic variables need further study. Studies of epilepsy etiology and classification mainly were performed without modern imaging tools. The best study found an overall standardized mortality ratio (SMR) for epilepsy relative to the general population of 2.3. There is evidence to suggest a greater increase in patients with symptomatic epilepsy, particularly children. People with epilepsy are more likely to report reduced Health-related Quality of Life than controls. They have reduced income, and are less likely to have full-time employment. They suffer from persistent stigma throughout the region, in developed as well as developing countries. Poor treatment access and health care disparities for people with epilepsy may be related to insufficient economic resources, rural isolation, gender, ethnicity, and lack of public and physician knowledge of modern approaches to epilepsy care. Despite high costs and severe disability, epilepsy may attract somewhat less research funding from public and private sources than other less common chronic neurological disorders. A Plan for Epilepsy in North America should address: basic and clinical research; primary prevention research; translation to care; stigma, quality of life, and self-management; industry relations; government and regional relations; and regional integration and resource sharing.

Pharmacological treatment of childhood absence epilepsy

This review discusses current pharmacological treatment of childhood absence epilepsy (CAE). The key to successful treatment is the correct diagnosis of the epileptic syndrome, hence the initial part of the paper discusses the definition, diagnostic criteria and epidemiology. This is followed by a detailed analysis of pharmacological agents used in the treatment of CAE. The characteristics of old and new anticonvulsants used in the treatment of CAE are also reviewed. For each of the drugs, the mechanism of action, usual dose, common side effects and recommendations for treatment are also discussed. A separate section focuses on instances when anticonvulsants may exacerbate seizures. Particular emphasis is given to the evidence currently available, on which clinical practice needs to be based.

ILAE classification of epilepsy syndromes

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

How long does it take for epilepsy to become intractable? A prospective investigation

OBJECTIVE

To determine prospectively when in the course of epilepsy intractability becomes apparent.

METHODS

Data are from a prospective cohort of 613 children followed for a median of 9.7 years. Epilepsy syndromes were grouped: focal, idiopathic, catastrophic, and other. Intractability was defined in two ways: (1) 2 drugs failed, 1 seizure/month, on average, for 18 months (stringent), and (2) failure of 2 drugs. Delayed intractability was defined as 3 or more years after epilepsy diagnosis.

RESULTS

Eighty-three children (13.8%) met the stringent and 142 (23.2%) met the two-drug definition. Intractability depended on syndrome (p < 0.0001): 26 (31.3%) children meeting stringent and 39 (27.5%) meeting the 2-drug definition had delayed intractability. Intractability was delayed more often in focal than catastrophic epilepsy (stringent: 46.2 vs 14.3%, p = 0.003; two-drug: 40.3 vs 2.2%, p <or= 0.0001). Early remission periods preceded delayed intractability in 65.4 to 74.3% of cases. After becoming intractable, 20.5% subsequently entered remission and 13.3% were seizure free at last contact.

INTERPRETATION

Intractable epilepsy may be delayed, especially in focal epilepsy. It often is preceded by a quiescent period, followed by further remissions. These findings help explain why surgically treatable epilepsies may take 20 years or longer before referral to surgery.

Epilepsy syndromes in infancy

An increasing number of infantile epilepsy syndromes have been recognized. However, a significant number of infants (children aged 1-24 months) do not fit in any of the currently used subcategories. This article reviews the clinical presentation, electroencephalographic findings, evolution, and management of the following entities: early infantile epileptic encephalopathy, early myoclonic epilepsy, infantile spasms/West syndrome, severe myoclonic epilepsy of infancy, myoclonic-astatic epilepsy, generalized epilepsy with febrile seizures plus, malignant migrating partial seizures of infancy, hemiconvulsions-hemiplegia-epilepsy, benign myoclonic epilepsy, and benign familial/nonfamilial infantile seizures. Issues related to their classification are addressed.

[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.

[Newly treated epilepsy: a French observational study]

AIMS

To assess the characteristic features of epileptic patients treated for the first time with oral anti-epileptic treatments. Patients and methods. All outpatients (adults and children), who consulted for epileptic attacks and for whom an oral anti-epileptic treatment was necessary, as a first time prescription, were enrolled consecutively in this study from April 2001 up to January 2003. Data were available from a structured questionnaire delivered to all participating neurologists.

RESULTS

Two hundred sixty neurologists included 2220 patients (1162 males, 1057 females with a mean age of 41 years (from 1 month to 96 years). Forty-one percent of these patients were referred by a general practitioner and 22 percent by emergency departments. Four hundred and thirty-seven patients (19.7 percent) had only experienced a single seizure at treatment initiation. Patients were classified according to focal epilepsy (43.9 percent of patients), generalized epilepsy (46.4 percent of patients), or non-classified epilepsy (9.7 percent of patients). Sixty-six percent of patients had a biological check-up. Ninety-three percent of patients underwent an EEG and 80.7 per cent a CT scan or brain MRI. The high risk of recurrence was the main reason given by neurologists for instituting anti-epileptic treatment. The reason for initiating treatment was syndromic diagnosis in 23.7 percent of patients with multiple seizures. The most frequently prescribed drug was valproic acid (58.2 percent of patients) chosen because of its practical use and broad anti-epileptic spectrum.

CONCLUSION

This study provides a considerable amount of epidemiological and clinical information with a special emphasis on epilepsy syndromes, diagnostic assessment and factors that influence the initiation of treatment or not.

Epilepsy in children

10.5 million children worldwide are estimated to have active epilepsy. Over the past 15 years, syndrome-oriented clinical and EEG diagnosis, and better aetiological diagnosis, especially supported by neuroimaging, has helped to clarify the diversity of epilepsy in children, and has improved management. Perinatal and postinfective encephalopathy, cortical dysplasia, and hippocampal sclerosis account for the most severe symptomatic epilepsies. Ion channel defects can underlie both benign age-related disorders and severe epileptic encephalopathies with a progressive disturbance in cerebral function. However, the reasons for age-related expression in children are not understood. Neither are the mechanisms whereby an epileptic encephalopathy originates. Several new drugs have been recently introduced but have provided limited therapeutic benefits. However, treatment and quality of life have improved because the syndrome-specific efficacy profile of drugs is better known, and there is heightened awareness that compounds with severe cognitive side-effects and heavy polytherapies should be avoided. Epilepsy surgery is an important option for a few well-selected individuals, but should be considered with great caution when there is no apparent underlying brain lesion.

Defining Intractability: Comparisons among Published Definitions

PURPOSE

Intractable epilepsy is the focus of much research; however, this concept is defined in no single way. Individual studies use different definitions, creating difficulties for comparisons of results across studies. A head-to-head comparison of definitions could highlight these differences and motivate the development of consensus guidelines.

METHODS

Within a single prospective study of 613 children in Connecticut with newly diagnosed epilepsy (1993-1997), six different published definitions or indicators for intractability were applied and compared. All definitions were assessed at various times within the first 5 years after diagnosis, with the exact timing reflecting how they were used in their initial reports. Observed and chance-adjusted agreement (kappa) were computed. The associations of each definition with remission status 7-10 years after diagnosis were quantified with a relative risk.

RESULTS

Depending on the specific definition, the epilepsy of 9-24% of children was considered intractable. Observed agreements among the definitions ranged from a low of 0.83 to a high of 0.96. Kappas ranged from low of 0.45 to 0.79. More similar definitions had higher levels of agreement. All definitions were strongly associated with remission status as of last follow-up.

CONCLUSIONS

Agreement among the different definitions is strong but imperfect. All definitions were significantly associated with longer-term outcome. No single preferred definition of intractable epilepsy exists. Some discussion within the field of epilepsy and a consensus process should be considered as a future step for enhancing comparability of research efforts and clinical guidelines. Consideration should be given to whether a single definition will suit all purposes or whether different types of definitions are needed for different purposes.

Challenges and opportunities in the application of pharmacogenetics to antiepileptic drug therapy

The recent surge of interest in pharmacogenetics has provoked considerable thought regarding its relevance to antiepileptic drug (AED) therapy. Initial studies have focused on genes whose products play a putatively important role in AED pharmacology, particularly drug transporter proteins, drug metabolizing enzymes and ion channel subunits. However, there is a lack of good correspondence between results from different laboratories, and more recent findings are awaiting attempts at confirmation. Thus, there are currently no AED treatment guidelines that are informed by pharmacogenetic data. In order to begin to have clinical impact, standards specific to the conduct of future AED studies must be established. Of particular importance are the need for accurate epilepsy classification, appropriate AED selection and clear and objective assessment outcome measures. In addition, general standards for analysis and interpretation of genetic association data must be better codified and applied consistently across studies. Finally, extensive clinical research networks must be formulated and large numbers of well characterized patients must be recruited. Further development of these critical factors will optimize chances for overcoming current challenges posed by AED pharmacogenetic research and ultimately allow the realization of improved, more rational therapeutic strategies.

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.