Risk factors for complex partial seizures: a population-based case-control study

Heat-Shock Induces Granule Cell Dispersion and Microgliosis in Hippocampal Slice Cultures

Granule cell dispersion (GCD) has been found in the dentate gyrus (dg) of patients with temporal lobe epilepsy (TLE) and a history of febrile seizures but was also recently observed in pediatric patients that did not suffer from epilepsy. This indicates that GCD might not always be disease related, but instead could reflect normal morphological variation. Thus, distribution of newborn granule cells within the hilar region is part of normal dg development at early stages but could be misinterpreted as pathological GCD. In turn, pathological GCD may be caused, for example, by genetic mutations, such as the reeler mutation. GCD in the reeler mutant goes along with an increased susceptibility to epileptiform activity. Pathological GCD in combination with epilepsy is caused by experimental administration of the glutamate receptor agonist kainic acid in rodents. In consequence, the interpretation of GCD and the role of febrile seizures remain controversial. Here, we asked whether febrile temperatures alone might be sufficient to trigger GCD and used hippocampal slice cultures as in vitro model to analyze the effect of a transient temperature increase on the dg morphology. We found that a heat-shock of 41°C for 6 h was sufficient to induce GCD and degeneration of a fraction of granule cells. Both of these factors, broadening of the granule cell layer (gcl) and increased neuronal cell death within the gcl, contributed to the development of a significantly reduced packaging density of granule cells. In contrast, Reelin expressing Cajal–Retzius (CR) cells in the molecular layer were heat-shock resistant. Thus, their number was not reduced, and we did not detect degenerating CR cells after heat-shock, implying that GCD was not caused by the loss of CR cells. Importantly, the heat-shock-induced deterioration of dg morphology was accompanied by a massive microgliosis, reflecting a robust heat-shock-induced immune response. In contrast, in the study that reported on GCD as a non-specific finding in pediatric patients, no microglia reaction was observed. Thus, our findings underpin the importance of microglia as a marker to distinguish pathological GCD from normal morphological variation.

Perisylvian vulnerability to postencephalitic epilepsy

OBJECTIVE

Postencephalitic epilepsy is often resistant to antiseizure medications, leading to evaluation for epilepsy surgery. Characterizing its localization carries implications for optimal surgical approach. We aimed to determine whether a prior history of encephalitis is associated with specific epileptogenic networks among patients with drug resistant epilepsy undergoing stereotactic EEG (SEEG).

METHODS

We conducted a retrospective cohort study of drug resistant epilepsy, with and without a prior history of encephalitis. We analyzed SEEG recordings to identify patterns of seizure onset and organization. Seventeen patients with a history of encephalitis (of infectious etiology in two subjects) were identified from a database of patients undergoing SEEG and were compared to seventeen drug-resistant epilepsy controls without a history of encephalitis matched for confounding variables including pre-implantation hypotheses, epilepsy duration, age, and sex.

RESULTS

Independent bilateral seizures were noted in 65% of the postencephalitic epilepsy cohort. We identified four SEEG-ictal patterns in patients with a prior history of encephalitis: (1) anteromesial temporal onset (24%), (2) anteromesial temporal onset with early spread to the perisylvian region (29%), (3) perisylvian (59%) and (4) synchronized anteromesial temporal and perisylvian (29%) onsets. Patterns 3 and 4, with perisylvian involvement at onset, were unique to the encephalitis group (p = 0.0003 and 0.04 respectively) and exhibited a "patchwork" organization. None of the encephalitis patients vs 5/7 matched controls had Engel I outcome (p = 0.0048).

CONCLUSIONS

Postencephalitic epilepsies involve anteromesial temporal and perisylvian networks, often in a bilateral independent manner. Unique ictal patterns involving the perisylvian regions was identified in the encephalitis group, but not in the matched control group.

SIGNIFICANCE

These findings may reflect a selective vulnerability of the perisylvian regions to epilepsy resulting from encephalitis, significantly mitigating the chances of success with SEEG-guided temporal resections.

Epilepsy, birth weight and academic school readiness in Canadian children: Data from the national longitudinal study of children and youth

PURPOSE

Birth weight is an important indicator of prenatal/in-utero environment. Variations in birth weight have been reportedly associated with risks for cognitive problems. The National Longitudinal Survey of Children and Youth (NLSCY) dataset was explored to examine relationships between birth weight, academic school readiness and epilepsy.

METHODS

A population based sample of 32,900 children of the NLSCY were analyzed to examine associations between birth weight, and school readiness scores in 4-5-year-old children. Logistic and Linear regression was used to examine associations between having epilepsy and these outcomes. Gestation data was available on 19,867 children, full-term children represented 89.67% (gestation >259days), while 10.33% of children were premature (gestation <258days). There were 20 children with reported epilepsy in the sample. Effects of confounding variables (diabetes in pregnancy, smoking in pregnancy, high blood pressure during pregnancy, and gender of the infant) on birth weight and epilepsy were controlled using a separate structural equation model.

RESULTS

Logistic regression analysis identified an association between epilepsy and lower birth weights, as well as an association between lower birth weight, having epilepsy and lower PPVT-R Scores. Model results show the relationship between low birth weight and epilepsy remains statistically significant even when controlling for the influence of afore mentioned confounding variables.

CONCLUSION

Low birth weight appears to be associated with both epilepsy and academic school readiness. The data suggest that an abnormal prenatal environment can influence both childhood onset of epilepsy and cognition. Additional studies with larger sample sizes are needed to verify this relationship in detail.

Pro-epileptogenic effects of viral-like inflammation in both mature and immature brains

BACKGROUND

Infectious encephalitides are most often associated with acute seizures during the infection period and are risk factors for the development of epilepsy at later times. Mechanisms of viral encephalitis-induced epileptogenesis are poorly understood. Here, we evaluated the contribution of viral encephalitis-associated inflammation to ictogenesis and epileptogenesis using a rapid kindling protocol in rats. In addition, we examined whether minocycline can improve outcomes of viral-like brain inflammation.

METHODS

To produce viral-like inflammation, polyinosinic-polycytidylic acid (PIC), a toll-like receptor 3 (TLR3) agonist, was applied to microglial/macrophage cell cultures and to the hippocampus of postnatal day 13 (P13) and postnatal day 74 (P74) rats. Cell cultures permit the examination of the inflammation induced by PIC, while the in vivo setting better suits the analysis of cytokine production and the effects of inflammation on epileptogenesis. Minocycline (50 mg/kg) was injected intraperitoneally for 3 consecutive days prior to the kindling procedure to evaluate its effects on inflammation and epileptogenesis.

RESULTS

PIC injection facilitated kindling epileptogenesis, which was evident as an increase in the number of full limbic seizures at both ages. Furthermore, in P14 rats, we observed a faster seizure onset and prolonged retention of the kindling state. PIC administration also led to an increase in interleukin 1β (IL-1β) levels in the hippocampus in P14 and P75 rats. Treatment with minocycline reversed neither the pro-epileptogenic effects of PIC nor the increase of IL-1β in the hippocampus in both P14 and P75 rats.

CONCLUSIONS

Hippocampal injection of PIC facilitates rapid kindling epileptogenesis at both P14 and P75, suggesting that viral-induced inflammation increases epileptogenesis irrespective of brain maturation. Minocycline, however, was unable to reverse the increase of epileptogenesis, which might be linked to its absence of effect on hippocampal IL-1β levels at both ages.

Epilepsy in children with a history of febrile seizures

PURPOSE

Febrile seizure, the most common type of pediatric convulsive disorder, is a benign seizure syndrome distinct from epilepsy. However, as epilepsy is also common during childhood, we aimed to identify the prognostic factors that can predict epilepsy in children with febrile seizures.

METHODS

The study comprised 249 children at the Korea University Ansan Hospital who presented with febrile seizures. The relationship between the subsequent occurrence of epilepsy and clinical factors including seizure and fever-related variables were analyzed by multivariate analysis.

RESULTS

Twenty-five patients (10.0%) had additional afebrile seizures later and were diagnosed with epilepsy. The subsequent occurrence of epilepsy in patients with a history of febrile seizures was associated with a seizure frequency of more than 10 times during the first 2 years after seizure onset (P<0.001). Factors that were associated with subsequent occurrence of epilepsy were developmental delay (P<0.001), preterm birth (P=0.001), multiple seizures during a febrile seizure attack (P=0.005), and epileptiform discharges on electroencephalography (EEG) (P=0.008). Other factors such as the age at onset of first seizure, seizure duration, and family history of epilepsy were not associated with subsequent occurrence of epilepsy in this study.

CONCLUSION

Febrile seizures are common and mostly benign. However, careful observation is needed, particularly for prediction of subsequent epileptic episodes in patients with frequent febrile seizures with known risk factors, such as developmental delay, history of preterm birth, several attacks during a febrile episode, and epileptiform discharges on EEG.

Long-term neurocognitive outcome and auditory event-related potentials after complex febrile seizures in children

OBJECTIVES

Whether prolonged or complex febrile seizures (FS) produce long-term injury to the hippocampus is a critical question concerning the neurocognitive outcome of these seizures. Long-term event-related evoked potential (ERP) recording from the scalp is a noninvasive technique reflecting the sensory and cognitive processes associated with attention tasks. This study aimed to investigate the long-term outcome of neurocognitive and attention functions and evaluated auditory event-related potentials in children who have experienced complex FS in comparison with other types of FS.

METHODS

One hundred and forty-seven children aged more than 6 years who had experienced complex FS, simple single FS, simple recurrent FS, or afebrile seizures (AFS) after FS and age-matched healthy controls were enrolled. Patients were evaluated with Wechsler Intelligence Scale for Children (WISC; Chinese WISC-IV) scores, behavior test scores (Chinese version of Conners' continuous performance test, CPT II V.5), and behavior rating scales. Auditory ERPs were recorded in each patient.

RESULTS

Patients who had experienced complex FS exhibited significantly lower full-scale intelligence quotient (FSIQ), perceptual reasoning index, and working memory index scores than did the control group but did not show significant differences in CPT scores, behavior rating scales, or ERP latencies and amplitude compared with the other groups with FS. We found a significant decrease in the FSIQ and four indices of the WISC-IV, higher behavior rating scales, a trend of increased CPT II scores, and significantly delayed P300 latency and reduced P300 amplitude in the patients with AFS after FS.

CONCLUSION

We conclude that there is an effect on cognitive function in children who have experienced complex FS and patients who developed AFS after FS. The results indicated that the WISC-IV is more sensitive in detecting cognitive abnormality than ERP. Cognition impairment, including perceptual reasoning and working memory defects, was identified in patients with prolonged, multiple, or focal FS. These results may have implications for the pathogenesis of complex FS. Further comprehensive psychological evaluation and educational programs are suggested.

Inflammation and epilepsy in the developing brain: clinical and experimental evidence

There is an increasing evidence to support a role of inflammatory processes in epilepsy. However, most clinical and experimental studies have been conducted in adult patients or using adult rodents. The pediatric epilepsies constitute a varied group of diseases that are most frequently age specific. In this review, we will focus on the possible role of inflammation in pediatric epilepsy syndromes. We will first describe the clinical data available and provide an overview of our current understanding of the role of inflammation in these clinical situations. We will then review experimental data regarding the role of inflammation in epilepsy in the developing brain. To summarize, inflammation contributes to seizure precipitation, and reciprocally, prolonged seizures induce inflammation. There is also a relationship between inflammation and cell injury following status epilepticus, which differs according to the developmental stage. Finally, inflammation seems to contribute to epileptogenesis even in the developing brain. Based on the available data, we highlight the need for further studies dissecting the exact role of inflammation in epilepsy during development.

Prognostic factors for subsequent epilepsy in children with febrile seizures

OBJECTIVE

Epilepsy following febrile seizures (FS) has been estimated between 2% and 7%. It concerns a prospective study in a large sample of children with a long-term follow-up. The aim of this study is to identify the prognostic factors that can lead children with FS to epilepsy.

METHODS

Children with a first episode of FS were included. We gathered information about prenatal and perinatal history, family history of FS and epilepsy in first- and second degree relatives, age at the time of the initial FS, dates of FS recurrences, focality, duration of the FS and recurrent episodes within the same febrile illness, height and duration of fever prior to the seizure, cause of the fever, and frequency of febrile illnesses. Patients were seen every 4-6 months and also at each recurrence.

KEY FINDINGS

A group of 560 children with a first FS met all entry criteria. Epilepsy was recorded at 5.4%. Statistical analysis was performed between children with epilepsy and those with no afebrile seizure. We analyzed FS recurrences in accordance with the occurrence of epilepsy. From the third FS recurrence and beyond, only focality continued to have prognostic value.

SIGNIFICANCE

Main prognostic factors for the development of epilepsy after FS are: (1) complex FS that increased the risk for epilepsy 3.6 times, (2) age at onset of FS beyond the third year of life that raised the risk 3.8 times, (3) positive family history of epilepsy 7.3 times, and (4) multiple episodes of FS about 10 times. Focality at the first and the second FS recurrence increased the risk of epilepsy about 9.7 and 11.7 times, respectively. Focality was the only factor that continued to be significant in further FS recurrences. A prognostic profile of each child with FS would be very useful for the follow-up of these children.

Preterm birth and risk of epilepsy in Swedish adults

OBJECTIVE

To determine whether preterm birth is associated with epilepsy in a national cohort of adults aged 25-37 years.

METHODS

We conducted a national cohort study of 630,090 infants born in Sweden from 1973 through 1979, including 27,953 born preterm (<37 weeks), followed from 2005 to 2009 for 1) hospitalization for epilepsy and 2) outpatient and inpatient prescription of antiepileptic drugs. Epilepsy diagnoses and medication data were obtained from all hospitals and pharmacies throughout Sweden.

RESULTS

We found a strong association between preterm birth and epilepsy that increased by earlier gestational age. After adjusting for fetal growth and potential confounders, odds ratios for hospitalization for epilepsy were 4.98 (95%confidence interval [CI] 2.87-8.62) for those born at 23-31 weeks, 1.98 (95% CI 1.26-3.13) for those born at 32-34 weeks, and 1.76 (95% CI 1.30-2.38) for those born at 35-36 weeks, relative to those born full-term (37-42 weeks). A similar but slightly weaker trend was observed for the association between preterm birth and antiepileptic drug prescription. These associations persisted after excluding individuals with cerebral palsy, inflammatory diseases of the CNS, cerebrovascular disease, and brain tumors.

CONCLUSIONS

These findings suggest that preterm birth, including late preterm birth, is strongly associated with epilepsy in Swedish adults aged 25-37 years. This association was independent of fetal growth and was not mediated by cerebral palsy or other comorbidities.

Hyperthermic effects on behavior

This review focuses upon the past 8 years of research on hyperthermic effects on behavior. Heat stress and heat stoke become severe conditions when body temperatures exceed 40°C as this can lead to delirium, convulsions, coma, and death. The animal literature indicates that hyperthermia can increase glutamatergic and decrease GABAergic neurotransmission. Interestingly, µ-opiate receptor antagonists can attenuate the morphological and biochemical changes in brain, as well as, ameliorate some behavioral deficits induced by heart stress. In humans, heat stress can produce detrimental effects on motor and cognitive performance. Since most cognitive tasks require a motor response, some cognitive deficiencies may be attributed to decreased motor performance. Although hyperthermia may exert more deleterious effects on complex than simple cognitive tasks, systematic studies are needed to examine the effects of different levels and durations of hyperthermia (irrespective of dehydration) on cognition. Additionally, body temperatures should be carefully monitored where controls are run for baseline or brief exposures to a hyperthermic environment. Acute radiofrequency exposure can disrupt behavior when body temperatures increase >1°C with whole body SAR between 3.2-8.4 W/kg and time-averaged power densities at 8-140 mW/cm(2). Effects of lower levels of radiation are conflicting and some experiments fail to replicate even with the original investigators. This suggests either that brief exposure to the radiation is at a threshold where some individuals are affected while others are not, or that these levels are innocuous. Nevertheless, thermal changes appear to account for almost all of the behavioral effects reported.

Sesamin ameliorates oxidative stress and mortality in kainic acid-induced status epilepticus by inhibition of MAPK and COX-2 activation

BACKGROUND

Kainic acid (KA)-induced status epilepticus (SE) was involved with release of free radicals. Sesamin is a well-known antioxidant from sesame seeds and it scavenges free radicals in several brain injury models. However the neuroprotective mechanism of sesamin to KA-induced seizure has not been studied.

METHODS

Rodents (male FVB mice and Sprague-Dawley rats) were fed with sesamin extract (90% of sesamin and 10% sesamolin), 15 mg/kg or 30 mg/kg, for 3 days before KA subcutaneous injection. The effect of sesamin on KA-induced cell injury was also investigated on several cellular pathways including neuronal plasticity (RhoA), neurodegeneration (Caspase-3), and inflammation (COX-2) in PC12 cells and microglial BV-2 cells.

RESULTS

Treatment with sesamin extract (30 mg/kg) significantly increased plasma α-tocopherol level 50% and 55.8% from rats without and with KA treatment, respectively. It also decreased malondialdehyde (MDA) from 145% to 117% (p=0.017) and preserved superoxide dismutase from 55% of the vehicle control mice to 81% of sesamin-treated mice, respectively to the normal levels (p=0.013). The treatment significantly decreased the mortality from 22% to 0% in rats. Sesamin was effective to protect PC12 cells and BV-2 cells from KA-injury in a dose-dependent manner. It decreased the release of Ca2+, reactive oxygen species, and MDA from PC12 cells. Western blot analysis revealed that sesamin significantly reduced ERK1/2, p38 mitogen-activated protein kinases, Caspase-3, and COX-2 expression in both cells and RhoA expression in BV-2 cells. Furthermore, Sesamin was able to reduce PGE2 production from both cells under KA-stimulation.

CONCLUSIONS

Taken together, it suggests that sesamin could protect KA-induced brain injury through anti-inflammatory and partially antioxidative mechanisms.

Predictors of a nondiagnostic epilepsy monitoring study and yield of repeat study

OBJECTIVE

Failure to record typical events during long-term video/EEG monitoring (LTM) leaves the diagnosis uncertain. The purpose of this study was to analyze predictors of an initial nondiagnostic LTM study and to evaluate the yield of a repeat study.

METHODS

We reviewed all adult LTM studies performed at Vanderbilt University from January 2004 to June 2008. We identified 150 patients with no typical events on LTM and matched them with consecutive controls with typical events. We compared patient demographics, epilepsy risk factors, history of antiepileptic use/failures, and prior EEG and MRI results.

RESULTS

Of 2397 LTM studies, 380 (15.8%) failed to record typical events. Absence of epilepsy risk factors and normal outpatient EEG predicted this outcome. A repeat LTM study was successful in 18 of 45 patients (42%).

CONCLUSION

The prediction of a nondiagnostic LTM can help to reduce the cost of investigating spells of unknown nature.

The remarkably high prevalence of epilepsy and seizure history in fetal alcohol spectrum disorders

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is the umbrella term that describes the range of adverse developmental outcomes that may occur in the offspring of mothers who drink alcohol during pregnancy. FASD is associated with several comorbidities including epilepsy. The objective of the study was to evaluate the prevalence of epilepsy or a history of seizures in subjects with FASD and the contribution of relevant risk factors.

METHODS

A retrospective chart review was conducted on all active charts (N = 1063) at two FASD clinics. After exclusion of subjects without a confirmed diagnosis, a total of 425 subjects between the ages of 2-49 were included in the analysis. The relationships between FASD diagnosis and other risk factors for co-occurrence of epilepsy or a seizure disorder (e.g., extent of exposure to alcohol and other drugs, type of birth, and trauma) were examined using chi-square and multivariate multinomial logistic regression.

RESULTS

Twenty-five (5.9%) individuals in the study population had a confirmed diagnosis of epilepsy, and 50 (11.8%) had at least one documented seizure episode, yielding an overall prevalence of 17.7% in this population. Importantly, a history of epilepsy or seizures was not different across the three diagnostic subgroups. In those subjects with available maternal drinking histories, first trimester exposure or drinking throughout all three trimesters were the predominant forms of fetal exposure. None of the other risk factors were associated with a greater prevalence of epilepsy or seizures.

CONCLUSIONS

There is a remarkably high prevalence of epilepsy/seizures in the FASD population.

Risk factors for epilepsy: a population-based case-control study in Kerala, southern India

We undertook a community-based case-control study on persons with active epilepsy residing in Kerala, southern India. Using a standardized questionnaire, we collected information from 362 cases and 362 controls. In the final multivariate model, family history of epilepsy (odds ratio=7.8, 95% confidence interval=3.2-18.8, P=0.000), antecedent history of febrile seizures (7.7, 4.3-14.0, 0.000), birth by complicated delivery (6.8, 2.1-21.8, 0.001), and neonatal seizures (7.8, 1.7-35.4, 008) emerged as strong independent predictors of epilepsy, followed in decreasing order by mental retardation, prematurity, maternal age 30, perinatal distress, and incomplete immunization. There were more similarities than differences in the distribution of risk factors between generalized and localization-related epilepsy syndromes. Our findings suggest interplay between genetic and acquired factors in the pathogenesis of epilepsies, and underscore the need for improvement in obstetric and neonatal care to minimize the epilepsy burden in low-income countries.

Viral-like brain inflammation during development causes increased seizure susceptibility in adult rats

Viral infections of the CNS and their accompanying inflammation can cause long-term neurological effects, including increased risk for seizures. To examine the effects of CNS inflammation, we infused polyinosinic:polycytidylic acid, intracerebroventricularly to mimic a viral CNS infection in 14 day-old rats. This caused fever and an increase in the pro-inflammatory cytokine, interleukin (IL)-1beta in the brain. As young adults, these animals were more susceptible to lithium-pilocarpine and pentylenetetrazol-induced seizures and showed memory deficits in fear conditioning. Whereas there was no alteration in adult hippocampal cytokine levels, we found a marked increase in NMDA (NR2A and C) and AMPA (GluR1) glutamate receptor subunit mRNA expression. The increase in seizure susceptibility, glutamate receptor subunits, and hippocampal IL-1beta levels were suppressed by neonatal systemic minocycline. Thus, a novel model of viral CNS inflammation reveals pathophysiological relationships between brain cytokines, glutamate receptors, behaviour and seizures, which can be attenuated by anti-inflammatory agents like minocycline.

Health, wealth, and culture as predominant factors in psychosocial morbidity

Depression is the most common psychological morbidity in epilepsy, yet this comorbidity is not well understood. Possible explanations for this comorbidity include recurrence of premorbid depression, increased risk for severe epilepsy due to a history of depression, shared risk factors for depression and epilepsy, AED-induced depression in vulnerable individuals, and coping styles in the face of stressors linked to epilepsy. Preexisting vulnerability to depression may contribute to each of these explanations. Vulnerability may arise from the influence of common risk factors, family history of depression, a history of depression before initiation of relevant AEDs, or coping styles and may reflect allostatic load. These exposures may precede the occurrence of epilepsy or follow the onset of epilepsy, in both cases increasing the risk for depression in prevalent epilepsy. Their careful evaluation is vital to identifying people at greatest risk for depression in epilepsy and for informing interventions to prevent the occurrence of this disabling epilepsy comorbidity.

Risk factors for a first epileptic seizure after stroke: a case control study

INTRODUCTION

The risk of seizures increases after stroke, but not all risk factors are known. We aimed to identify factors that increase the risk of a first seizure after a stroke.

METHODS

Multicenter case-control study of 161 patients with a first seizure after stroke (105 provoked/acute and 56 unprovoked/remote symptomatic) matched to 279 hospital stroke controls by center, gender, age and timing of stroke.

RESULTS

The risk of first seizure (odds ratio (OR), 95% confidence limits (CL)) was 3.6 (2.4-5.5) for cortical involvement, 2.5 (1.2-5.3) for multiple CT-scan lesions, 2.4 (1.5-3.9) for supratentorial lesions, 2.4 (1.6-3.7) for prior lesions on CT-scan, 2.1 (1.1-4.7) for family history of seizures, 2.0 (1.1-3.6) for use of epileptogenic drugs, 1.7 (1.0-2.9) for large lesions, 1.6 (1.0-2.8) for hemorrhagic lesions, and 1.4 (1.0-2.2) for cortical atrophy. After multivariate analysis, including all the factors significant in univariate analysis, the strongest independent predictor of a first seizure was cortical involvement (OR 3.3; 95% CL=2.1-5.0), followed by prior lesions (2.2; 1.4-3.4) and hemorrhagic stroke (1.8, 1.0-3.2). The multivariate analysis model for remote symptomatic seizures included cortical involvement, large size, and prior lesions; the model for acute seizures included cortical involvement, alcohol consumption >50 g/day, hemorrhagic stroke, and prior lesions on CT-scan.

DISCUSSION

Cortical involvement, the presence of prior lesions on CT-scan, and hemorrhagic lesion are the most important risk factors for a first-ever seizure after stroke.

Preeclampsia and risk for epilepsy in offspring

OBJECTIVE

Eclampsia has been found to be a strong risk factor for epilepsy in the offspring, but it is unclear whether the risk also applies to the preceding condition, preeclampsia.

METHODS

We conducted a population-based cohort study of 1537860 singletons born in Denmark (1978-2004). Information on preeclampsia (mild, severe, and unspecified), eclampsia, and epilepsy was obtained from the Danish National Hospital Register. Information on gestational age, birth weight, and Apgar score was obtained from the Danish Medical Birth Registry. We used Cox proportional hazard models to estimate the incidence rate ratio of epilepsy for children who were exposed to preeclampsia or eclampsia in prenatal life.

RESULTS

We identified 45288 (2.9%) children who were exposed to preeclampsia (34823 to mild, 7043 to severe, and 3422 to unspecified preeclampsia) and 654 (0.04%) to eclampsia during their prenatal life. We identified 20260 people who received a diagnosis of epilepsy during up to 27 years of follow-up in the entire cohort. Prenatal exposure to preeclampsia was associated with an increased risk for epilepsy among children with a gestational age at birth of at least 37 weeks. For mild preeclampsia, the incidence rate ratios were 1.16 among children born at term and 1.68 for children born postterm; for severe preeclampsia, the incidence rate ratios were 1.41 among children born at term and 2.57 among children born postterm. No associations between preeclampsia and epilepsy were found among children who were born preterm. Eclampsia was associated with epilepsy with an incidence rate ratio of 1.29 for children born at term and 5.03 for children born postterm.

CONCLUSIONS

Prenatal exposure to both preeclampsia and eclampsia was associated with an increased risk of epilepsy in children born after 37 weeks of gestation.

Prenatal exposure to maternal infections and epilepsy in childhood: a population-based cohort study

OBJECTIVE

We estimated the association between prenatal exposure to maternal infections and the subsequent risk for epilepsy in childhood.

METHODS

We included 90,619 singletons who were born between September 1997 and June 2003 in the Danish National Birth Cohort and followed them up to December 2005. Information on maternal infections during pregnancy (cystitis, pyelonephritis, diarrhea, coughs lasting >1 week, vaginal yeast infection, genital herpes, venereal warts, and herpes labialis) was prospectively reported by mothers in 2 computer-assisted telephone interviews in early and midgestation; information on maternal cystitis and pyelonephritis during late period of pregnancy was also collected in a third interview after birth. Children who received a diagnosis of epilepsy as inpatients or outpatients were retrieved from the Danish National Hospital Register. We identified 646 children with a diagnosis of epilepsy during up to 8 years of follow-up time. Cox proportional hazards regression models were used to estimate incidence rate ratio and 95% confidence interval.

RESULTS

Children who were exposed to maternal cystitis, pyelonephritis, diarrhea, coughs, and/or vaginal yeast infection some maternal infections in prenatal life had an increased risk for epilepsy. Coughs lasting >1 week were associated with an increased risk for epilepsy only in the first year of life, as was vaginal yeast infection only in children who were born preterm. These associations remained unchanged for children without cerebral palsy, congenital malformation, or a low Apgar score at 5 minutes.

CONCLUSIONS

Prenatal exposure to some maternal infections was associated with an increased risk for epilepsy in childhood.

Gestational age, birth weight, intrauterine growth, and the risk of epilepsy

The authors evaluated the association between gestational age, birth weight, intrauterine growth, and epilepsy in a population-based cohort of 1.4 million singletons born in Denmark (1979-2002). A total of 14,334 inpatients (1979-2002) and outpatients (1995-2002) with epilepsy were registered in the Danish National Hospital Register. Children who were potentially growth restricted were identified through two methods: 1) sex-, birth-order-, and gestational-age-specific z score of birth weight; and 2) deviation from the expected birth weight estimated based on the birth weight of an older sibling. The incidence rates of epilepsy increased consistently with decreasing gestational age and birth weight. The incidence rate ratios of epilepsy in the first year of life were more than fivefold among children born at 22-32 weeks compared with 39-41 weeks and among children whose birth weight was <2,000 g compared with 3,000-3,999 g. The association was modified by age but remained into early adulthood. Incidence rate ratios of epilepsy were increased among children identified as growth restricted according to either of the two methods. In conclusion, short gestational age, low birth weight, and intrauterine growth restriction are associated with an increased risk of epilepsy.

Prevalence of some risk factors in children with epilepsy compared to their controls

AIM

The goal of this case-control study was to identify the significance of certain risk factors for epilepsy in Turkey.

METHOD

A total of 805 cases, aged 1-16 years, followed-up for epilepsy at the Pediatric Neurology Department and a control group consisting of 846 age-matched cases without epilepsy were included in the study. The risk factors examined were gender, neurological impairment, febrile convulsion, head trauma, central nervous system infections, parental consanguinity, family history of epilepsy, prenatal and natal risk and newborn jaundice. Data regarding the investigated epilepsy risk factors were obtained through a questionnaire via personal interviews and the medical records and were assessed using univariate and multivariate analysis.

RESULT

Univariate analysis showed an increased risk for epilepsy with a history of atypical febrile seizure (21.97-fold), severe and moderate head injury (27.76- and 7.09-fold respectively), CNS infection (4.76-fold), history of epilepsy in first-, second- or third-degree relatives (6.42-, 3.09- and 2.66-fold, respectively), presence of maternal hypertension (4.31-fold), an apgar score < or =6 at any time (7.78-fold) and neonatal jaundice (3.12-fold). Abnormal neurological signs increased the epilepsy risk 5.92 times in univariate analysis and 30.26 times in multivariate analysis.

CONCLUSION

The most important risk factors for epilepsy in this study were neurological impairment, history of atypical febrile seizures, severe head injury and a low apgar score. Other important risk factors were moderate head trauma and a history of epilepsy in the family.

Epilepsy and febrile seizures in children of treated and untreated subfertile couples

BACKGROUND

Only few studies have addressed the long-term neurological outcomes of children born by subfertile couples. We studied the risk of epilepsy and febrile seizures in children of treated and untreated subfertile couples.

METHODS

The study included 83 194 live singletons born by mothers who took part in the Danish National Birth Cohort (DNBC). Information on time to pregnancy (TTP) and infertility treatment was reported by the mothers in computer-assisted telephone interviews. Data on epilepsy and febrile seizures were extracted from the Danish National Hospital Register.

RESULTS

Overall, children of subfertile couples (TTP > 12 months) had a 51% higher risk of epilepsy [incidence rate ratio (IRR): 1.51; 95% confidence interval (95% CI): 1.17-1.94] compared with children of couples with a TTP of 0-5 months. The corresponding estimates were 1.71 (95% CI: 1.21-2.42) if the couples had received infertility treatment and 1.38 (95% CI: 1.00-1.89) if they conceived spontaneously. Children of subfertile couples did not have a higher risk of febrile seizures except for those who received hormonal treatment (HT) with or without intrauterine insemination (IRR = 1.37; 95% CI: 1.14-1.66).

CONCLUSIONS

Children of subfertile couples had a slightly increased risk of epilepsy, and the risk tended to be higher for children of couples who received infertility treatment. Whether this reflects side effects of treatment or severity of subfecundity is not known.

Decrease of hippocampal GABA B receptor-mediated inhibition after hyperthermia-induced seizures in immature rats

PURPOSE

Whether febrile seizures have detrimental consequences on the brain is still controversial. We hypothesized that neuronal inhibition in the hippocampus is altered after hyperthermia-induced seizures in immature rats.

METHODS

Rats were given a single seizure by a heat lamp on postnatal day (PND) 15, or repeated seizures by heated air on PND 13 to 15. Fourteen or 30 days after the seizure(s), laminar field potentials were recorded by 16-channel silicon probes in CA1 and the dentate gyrus (DG), in response to the paired-pulse stimulation of the CA3 and medial perforant path, and analyzed as current source density. Gamma-aminobutyric acid (GABA)(B)-receptor antagonist CGP35348 was injected intracerebroventricularly (icv).

RESULTS

At 14 but not at 30 days after a single or after repeated hyperthermia-induced seizures, paired-pulse facilitation (PPF) of the CA1 population spikes at 100 to 200 ms interpulse intervals (IPIs) was significantly increased in seizure as compared with control rats, irrespective of the types of induced seizures. CGP35348 icv also resulted in PPF at 100 to 200 ms IPIs in CA1 of control rats, but CGP35348 had no effect on PPF in seizure rats. At 30 days after repeated seizures, paired-pulse inhibition in the DG was significantly increased at 30-ms IPI, and PPF was increased at 200-ms IPI. CGP35348 increased paired-pulse inhibition in the DG in repeated-seizure rats but not in control rats.

CONCLUSIONS

We conclude that hyperthermia-induced seizures in immature rats induced a decrease of GABA(B) receptor-mediated inhibition in CA1 and DG that lasted > or =14 to 30 days after hyperthermic seizure(s).

Apgar Scores and Long-Term Risk of Epilepsy

BACKGROUND

Low Apgar scores are associated with high risk of neonatal death, cerebral palsy, and mental retardation, but the association between Apgar scores and long-term risk of epilepsy remains unresolved.

METHODS

We carried out a population-based cohort study of 1,538,732 live newborns in Denmark between 1 January 1978 and 31 December 2002 by using national registers. The Apgar scores at 1 or 5 minutes were recorded by midwives following standardized procedures. We obtained information on epilepsy by linking the cohort with the National Hospital Register. Cohort members were followed from birth until onset of epilepsy, death, emigration, or 31 December 2002, whichever came first.

RESULTS

The incidence rate of epilepsy increased consistently with decreasing Apgar scores. The incidence rate of epilepsy was 628 per 100,000 person-years for those with 5-minute Apgar scores of 1 to 3 and 86 per 100,000 person-years for those with a score of 10; the resulting incidence rate ratio was 7.1 (95% confidence interval = 5.8-8.8). The incidence rate ratios of epilepsy associated with low Apgar scores were particularly high in early childhood but remained high into adulthood. The association did not change after excluding children with cerebral palsy, congenital malformations, or a parental history of epilepsy.

CONCLUSIONS

Neonates with a suboptimal Apgar score have a higher risk of epilepsy that lasts into adult life. These findings suggest that prenatal or perinatal factors play a larger role in the etiology of epilepsy than has previously been recognized.

Risks for severe mental retardation occurring in isolation and with other developmental disabilities

Individual and maternal characteristics as potential risk factors for having severe mental retardation (SMR) occurring with and without cerebral palsy (CP), epilepsy, or a pervasive developmental disorder (PDD) were explored among a cohort of 119,404 children without Down syndrome born in the California Central Valley in 1992 and 1993. Unadjusted and adjusted relative risks (RRs) and their 95% confidence intervals (CIs) based on the Poisson distribution were used to estimate the risks associated with each individual and maternal factor studied for each SMR diagnostic category. The most notable increased risks for SMR occurring in isolation or with CP or epilepsy was for children born low-birth-weight or preterm who were at a substantially increased risk (RRs 2.6-9.9). In contrast, the risk of SMR occurring with a PDD was the greatest among males compared to females (RR = 3.4, 95% CI 1.5, 7.9), Blacks compared to Whites (RR = 5.1, 95% CI 1.7, 15.5), and Asians compared to Whites (RR = 3.9, 95% CI 1.3, 12.0). Etiologic heterogeneity when SMR occurs with a PDD was suggested.

Epilepsy and synaptic reorganization in a perinatal rat model of hypoxia-ischemia

PURPOSE

One of the potential consequences of perinatal hypoxia-ischemia (H-I) is the development of epilepsy, and synaptic reorganization in the hippocampus has been associated with epilepsy after an injury. We tested the hypothesis that perinatal H-I will induce spontaneous motor seizures, hippocampal lesions, and synaptic reorganization in the dentate gyrus.

METHODS

The right common carotid artery of 7-day-old rats was permanently ligated, and the rats were placed for 120 min into a chamber filled with 8% oxygen (37 degrees C). Animals were directly observed for chronic motor seizures for 7 to 24 months after the H-I insult.

RESULTS

Nearly half of the rats (i.e., eight of 20) were seen to have spontaneous motor seizures after the H-I injury. The ipsilateral hippocampi from both the rats with seizures and the rats not seen to have seizures had hippocampal lesions and increased amounts of Timm stain in the inner molecular layer (IML) compared with controls. The contralateral hippocampi from the rats with seizures, but not the hippocampi from the rats not seen to have seizures, had significantly increased amounts of Timm stain in the IML.

CONCLUSIONS

These results suggest that perinatal H-I can induce epilepsy, ipsilateral hippocampal lesions, and mossy fiber sprouting in the lesioned and contralateral hippocampus.

Valacyclovir treatment ameliorates the persistently increased pentylenetetrazol-induced seizure susceptibility in mice with herpes simplex virus type 1 infection

Herpes simplex virus type 1 (HSV-1) is an important pathogen related to epilepsy. We have shown previously that corneal inoculation of mice with HSV-1 causes acute spontaneous behavioral and electrophysiological seizures and increases hippocampal excitability and kainite-induced seizure susceptibility. In this study, we aimed to determine whether early-life HSV-1 infection in mice might cause short- and long-term enhanced susceptibility to pentylenetetrazol (PTZ)-induced seizures and to evaluate whether early antiviral drug therapy was effectively ameliorating this deficit. Seizure threshold was calculated by the latency of onset of the myoclonic jerk, generalized clonus, and maximal tonic-clonic convulsion. We demonstrate that the localization of viral antigens was predominantly within the bilateral temporal areas (amygdala, piriform, and entorhinal cortex) of HSV-1-infected mice. We also present evidence that mice of all HSV-1-infected groups had a shorter latency and higher severity to PTZ-induced seizures than in age-matched, mock-infected controls. Treatment of HSV-1-infected mice with valacyclovir, a potent inhibitor of HSV-1 replication, produced a dose-dependent decrease in the signs of neurological deficits, pathological damages, and PTZ-induced seizure severity. Our results are consistent with the hypothesis that early-life HSV-1 infection leads to persistent enhancement of neuronal excitability in limbic circuits, which could result in an overall increased propensity to induce seizures later in life. Additionally, prompt optimal antiviral therapy effectively decreases seizure susceptibility in HSV-1-infected mice by limiting the level of viral replication and inflammatory response induced by virus. The present study provides not only experimental evidence, but also a new therapeutic strategy in HSV-1-associated human epilepsy.

Fever, genes, and epilepsy

About 13% of patients with epilepsy have a history of febrile seizures (FS). Studies of familial forms suggest a genetic component to the epidemiological link. Indeed, in certain monogenic forms of FS, for which several loci have been reported, some patients develop epilepsy with a higher risk than in the general population. Patients with generalised epilepsy with febrile seizures plus (GEFS+) can have typical and isolated FS, FS lasting more beyond age 6 years, and subsequent afebrile (typically generalised) seizures. Mutations associated with GEFS+ were identified in genes for subunits of the voltage-gated sodium channel and the gamma2 subunit of the ligand-gated GABAA receptor. Screening for these genes in patients with severe myoclonic epilepsy in infancy showed de novo mutations of the alpha1 subunit of the voltage-gated sodium channel. Antecedent FS are commonly observed in temporal-lobe epilepsy (TLE). In sporadic mesial TLE-characterised by the sequence of complex FS in childhood, hippocampal sclerosis, and refractory temporal-lobe seizures-association studies suggested the role of several susceptibility genes. Work on some large pedigrees also suggests that FS and temporal-lobe seizures may have a common genetic basis, whether hippocampus sclerosis is present or not. The molecular defects identified in the genetic associations of FS and epileptic seizures are very attractive models to aid our understanding of epileptogenesis and susceptibility to seizure-provoking factors, especially fever.

Seizure, neuron loss, and mossy fiber sprouting in herpes simplex virus type 1-infected organotypic hippocampal cultures

PURPOSE

Epileptic seizures are frequently seen after viral encephalitis. Herpes simplex virus type 1 (HSV-1) encephalitis is the most common cause of acquired epilepsy in humans. However, little information is available about the neuropathogenesis of HSV-1-associated seizures. We have developed an in vitro HSV-1-infected organotypic hippocampal slice culture to elucidate the underlying mechanisms of HSV-1-associated acute seizure activity.

METHODS

Hippocampal slice cultures were prepared from postnatal day 10 to 12 rat pups. Wild-type HSV-1 strain RE (1 x 10(5) PFU) was applied to cultures at 14 days in vitro. The excitability of CA3 pyramidal cells and hippocampal network properties were measured with electrophysiological recordings. Hematoxylin-eosin (H&E) and Timm stains were used.

RESULTS

HSV-1 infection induces epileptiform activity, neuron loss, and subsequently a dramatic increase of mossy fiber sprouting in the supragranular area. With intracellular recordings, surviving CA3 pyramidal cells exhibited a more depolarizing resting membrane potential concomitant with an increase in membrane input resistance and had a lower threshold to generate synchronized bursts and a decrease in the amplitude of afterhyperpolarization than did controls. When the antiherpes agent acyclovir was applied with a delay of 1 or 24 h after HSV-1 infection, a dramatic inhibition of HSV-1 replication and protection of the neuron loss were observed.

CONCLUSIONS

These results suggest that a direct change in the excitability of the hippocampal CA3 neuronal network and HSV-1-induced neuron loss resulting in subsequent mossy fiber reorganization may play an important role in the generation of epileptiform activity.

Predicting outcome of initial treatment with carbamazepine in childhood focal epilepsy

We developed a model to predict the outcome of treatment with carbamazepine in children with newly diagnosed focal epilepsy of presumed temporal lobe origin, using data available at the time of diagnosis. Eligible children observed at The Children's Hospital of Philadelphia during 1999 were identified. Data were abstracted on four potential predictor variables for carbamazepine success or failure. A total of 149 patients completed an adequate first antiepileptic trial. Carbamazepine was the initial drug used in 129 (87%) patients. Forty-one of these 129 patients (32%) had persistent seizures. Significant predictors of initial carbamazepine failure were as follows: early risk factor for epilepsy (risk ratio = 3.1 [95% confidence interval 1.6, 4.0]) and temporal lobe abnormality on magnetic resonance imaging scan (risk ratio = 3.1 [1.7, 4.2]). The outcome of the initial carbamazepine trial was correctly classified in up to 78% of patients. Accurate prediction of initial carbamazepine failure was as high as 0.67 (0.53, 0.79). Accurate prediction of initial carbamazepine success was as high as 0.87 (0.77, 0.94). In this study, standard clinical data were less than adequate for predicting response to the initial trial of carbamazepine, with prediction of carbamazepine failure being particularly difficult. Better markers of antiepileptic response and nonresponse are required to guide optimal therapy in patients with epilepsy.

Febrile Seizures and Mechanisms of Epileptogenesis: Insights from an Animal Model

Temporal lobe epilepsy (TLE) is the most prevalent type of human epilepsy, yet the causes for its development, and the processes involved, are not known. Most individuals with TLE do not have a family history, suggesting that this limbic epilepsy is a consequence of acquired rather than genetic causes. Among suspected etiologies, febrile seizures have frequently been cited. This is due to the fact that retrospective analyses of adults with TLE have demonstrated a high prevalence (20-->60%) of a history of prolonged febrile seizures during early childhood, suggesting an etiological role for these seizures in the development of TLE. Specifically, neuronal damage induced by febrile seizures has been suggested as a mechanism for the development of mesial temporal sclerosis, the pathological hallmark of TLE. However, the statistical correlation between febrile seizures and TLE does not necessarily indicate a causal relationship. For example, preexisting (genetic or acquired) 'causes' that result independently in febrile seizures and in TLE would also result in tight statistical correlation. For obvious reasons, complex febrile seizures cannot be induced in the human, and studies of their mechanisms and of their consequences on brain molecules and circuits are severely limited. Therefore, an animal model was designed to study these seizures. The model reproduces the fundamental key elements of the human condition: the age specificity, the physiological temperatures seen in fevers of children, the length of the seizures and their lack of immediate morbidity. Neuroanatomical, molecular and functional methods have been used in this model to determine the consequences of prolonged febrile seizures on the survival and integrity of neurons, and on hyperexcitability in the hippocampal-limbic network. Experimental prolonged febrile seizures did not lead to death of any of the seizure-vulnerable populations in hippocampus, and the rate of neurogenesis was also unchanged. Neuronal function was altered sufficiently to promote synaptic reorganization of granule cells, and transient and long-term alterations in the expression of specific genes were observed. The contribution of these consequences of febrile seizures to the epileptogenic process is discussed.

Herpes simplex virus type 1 inoculation enhances hippocampal excitability and seizure susceptibility in mice

Herpes simplex virus type 1 (HSV-1) is the major pathogen related to epilepsy. However, little is known about the pathogenesis of HSV-1-associated epilepsy. Here, we report that corneal inoculation of mice with HSV-1 induces acute spontaneous behavioural and electrophysiological seizures and chronically increases hippocampal excitability and seizure susceptibility. In slices from infected mice, the surviving hippocampal CA3 pyramidal neurons exhibited a more depolarizing resting membrane potential concomitant with an increase in membrane input resistance. They also had a lower threshold for generating synchronized bursts and a decrease in the amplitude of afterhyperpolarization (AHP) than did controls. These results suggest that a direct change in the excitability of the hippocampal CA3 neuronal network could play an important role in facilitating the development of acute seizures and subsequent epilepsy.

Risk factors for childhood epilepsy: a case-control study from Irbid, Jordan

OBJECTIVE

The goal of this case-control study is to identify the significance of certain risk factors for epilepsy in a population of epileptic children in Northern Jordan. The risk factors examined are febrile convulsions, head trauma, central nervous system infections, abnormal perinatal history, family history and parental consanguinity.

METHODOLOGY

We designed a case-control study for patients attending the outpatient neurology clinic of Princess Rahma Teaching Hospital in Irbid, Jordan during a 7-month period. Controls were selected, matched for age and sex, from a group of non-epileptic patients attending the general paediatrics outpatient clinic in the same hospital and during the same period. Data about the investigated risk factors were obtained by personal interview and review of the medical records and were analysed statistically for significance.

RESULTS

The total number of participants was 200 patients and controls each. History of febrile convulsions, head trauma, abnormal perinatal history and family history showed a statistically significant increase risk for developing epilepsy. Central nervous system infections and parental consanguinity did not add to the risk of developing epilepsy.

CONCLUSION

Positive family history for epilepsy, head trauma, febrile convulsions and abnormal perinatal history were shown to have a statistically significant association with epilepsy in patients attending Princess Rahma Teaching Hospital in Northern Jordan. Although consanguinity is widely practised in Jordan, it appears that it does not increase the risk of epilepsy probably due to the small contribution of monogenic recessive epilepsies to the population with epilepsy.

Therapeutics in pediatric epilepsy, Part 2: Epilepsy surgery and vagus nerve stimulation

When antiepileptic drugs fail to relieve seizures adequately in children and adolescents, more invasive therapies such as epilepsy surgery and an implanted device to stimulate the vagus nerve should be considered. Temporal lobectomy is an effective treatment of complex partial and secondarily generalized tonic-clonic seizures arising in the mesial structures or lateral temporal neocortex. Excellent outcomes (seizure free or rare, nondisabling seizures) are achieved in at least 70% of children. The most common adverse effect is a superior quadrant field cut that is usually asymptomatic. Transient and more long-lasting language difficulties have been reported when the surgery involves the dominant temporal lobe. The excellent outcome rate for extratemporal surgery ranges from approximately 20% to 80%, with better results seen in patients with an identifiable lesion. Potential morbidity is related to the region of resected neocortex. Corpus callosotomy is an excellent procedure for palliation but is not a cure for seizures that cause falls, with substantial improvement seen in more than 80% of patients. Potential adverse effects include more intense focal seizures and dysphasia, depending on the developmental level of the individual. Hemispherectomy provides seizure relief in 60% to 80% of patients with hemispherical pathologies such as Sturge-Weber or Rasmussen syndromes. Operative mortality has been reported in the range of 0% to 6%; other morbidities include infection and hydrocephalus. Stimulation of the vagus nerve has reduced partial seizures by 50% or more in approximately one third of patients. No adverse cognitive or systemic effects are associated with use of the implanted vagus nerve stimulator.

The epidemiology of the epilepsies in children

The epilepsies are a heterogeneous collection of neurological conditions and syndromes characterized by recurrent, unprovoked, paroxysmal seizure activity. There are several types of epileptic seizures and syndromes that are unique to children, including infantile spasms, Lennox-Gastaut syndrome and absence seizures. Febrile seizures and neonatal seizures, while not epilepsy, are relatively common types of seizures in infants and children and are likely markers of risk of later epilepsy. Thus, it is important to consider the epidemiological features of the epilepsies as they occur specifically in infants and children. The purpose of this review is to summarize what is currently known about the epidemiology of the childhood epilepsies and to identify promising areas for further population-based studies. The epilepsies are an important cause of neurological morbidity in children. The average annual rate of new cases (incidence) of epilepsy is approximately 5-7 cases per 10,000 children from birth to age 15 years, and in any given year, about 5 of every 1,000 children will have epilepsy. There is evidence that the incidence of the epilepsies in some populations of children may be decreasing over time, and this possibility merits further investigation. Factors that are known to increase risk of the epilepsies in children include congenital malformations of the central nervous system (CNS), moderate or severe head trauma, CNS infections, certain inherited metabolic conditions, and genetic factors. However, these account for only 25% to 45% of cases, and thus, the etiology of most cases of the epilepsies remains obscure. The paucity of well-controlled etiological studies is due largely to formidable methodological problems in conducting epidemiological studies of the epilepsies. The prognosis for seizure control is generally good, although children with remote symptomatic seizures and those with additional neurological disabilities do less well.

The prevalence of epilepsy amongst school children in Izmir, Turkey

OBJECTIVE

The aim of this study was to assess the prevalence of epilepsy among school children between the ages of 7-17 in Izmir province, in Turkey.

METHODS

A cross sectional study was conducted. Sample size is calculated as 4654, from the target population of 420054 students. A stratified random sampling technique was used to select the schools located in Izmir Metropolitan area. For the 130 (2.8%) students whose families gave a positive 'epilepsy history' a telephone interview was conducted in order to verify the diagnosis and to evaluate a etiological factors.

RESULTS

Response rate was 90.5% (4216 students). Out of the 130 students who had a positive epilepsy history, 47 (36.2%) were accepted as epilepsy 'cases'. The crude prevalence rates for females, males and the total study population were found respectively to the 11.3, 11.1 and 11.2 per thousand. Prevalence of active epilepsy rates for females, males and total study population were found respectively to be 4.5, 7.0 and 5.6 per thousand.

CONCLUSION

The prevalence of epilepsy is higher in school-age children in Izmir province compared to that in developed countries.

Hyperthermia induces age-dependent changes in rat hippocampal excitability

The mechanisms underlying the generation of febrile seizures are poorly understood. This study investigated hyperthermia-induced changes in the hippocampus, a structure implicated in febrile seizures. It was hypothesized that neuronal excitability in the hippocampus changes with increasing temperature, and that this change is different in adult as compared with immature rats. Adult and immature (15-17 days postnatal) male rats were studied under urethane anesthesia during normothermia, moderate hyperthermia (38-39.5 degrees C), and severe hyperthermia (>39.5 degrees C). Paired-pulse inhibition of the orthodromically activated population spikes in the dentate gyrus and cornu ammonis 1 region of the hippocampus (CA1), two structures within the hippocampus, was measured after stimulation of the medial perforant path and Schaffer collaterals, respectively. In the adult rat, paired-pulse inhibition was increased in the dentate gyrus during moderate and severe hyperthermia but decreased in CA1 during severe hyperthermia (all p values < 0.05). In the immature rat, paired-pulse inhibition was unchanged in the dentate gyrus but decreased in CA1 during moderate hyperthermia (p < 0.05). We suggest that hyperthermia contributes to seizure susceptibility in the immature hippocampus by decreasing CA1 inhibition. In the adult rat, a decrease in CA1 inhibition requires a higher degree of hyperthermia, and hippocampal seizure generation is opposed by an increase in dentate gyrus inhibition.

Treating epilepsy in the elderly: safety considerations

The incidence of epilepsy increases with advancing age. Epilepsy in the elderly has different aetiologies from that in younger populations, cerebrovascular disease being the most common condition associated with seizures. Partial seizures are the predominant seizure type in older patients. A diagnosis of epilepsy in the elderly is based mainly on the history and is frequently delayed. In addition, seizure imitators are especially frequent. In many cases ancillary tests for diagnosis may show normal age-related variants, sometimes making results difficult to interpret. Treating epilepsy in the elderly is problematic due to a number of issues that relate to age and comorbidity. The physical changes associated with increasing age frequently lead to changes in the pharmacokinetics of many anticonvulsants. The treatment of epilepsy in the elderly is also complicated by the existence of other diseases that might affect the metabolism or excretion of anticonvulsants and the presence of concomitant medications that might interact with them. Moreover, specific trials of anticonvulsants in the aged population are scarce. General guidelines for treatment include starting at lower doses, slowing the titration schedule, individualising the choice of anticonvulsant to the characteristics of the patient, avoiding anticonvulsants with important cognitive or sedative adverse effects, and where possible, treating with monotherapy.

An incident case-control study of first unprovoked afebrile seizures in children: a population-based study of pre- and perinatal risk factors

PURPOSE

The aim of this prospective incident community-based study was to assess the influence of pre- and perinatal risk factors in children in whom an unprovoked afebrile epileptic seizure later developed.

METHODS

From November 1, 1985, until June 30, 1987, 75 children aged 0-15 years with a first unprovoked afebrile seizure were identified. After exclusion of cases with neonatal seizures (n = 14), two controls per case were selected from the same province in northern Sweden matched by age and sex. Files from maternity wards and pediatric clinics could be traced for 58 cases and 109 controls. These formed the study group.

RESULTS

In the univariate analysis, the risk for an unprovoked afebrile seizure was significantly elevated for birth order (OR = 9.3; CI, 2.2-39), vaginal bleeding (OR = 17; 95% CI, 3.5-85), onset of hypertension during pregnancy (OR = 4.8; CI, 1.3-17), cesarean section (OR = 18; 95% CI, 3.7-88), short or long gestational age (OR = 6.7; 95% CI, 2.0-22), and an Apgar score < or =6 at any time (OR = 3.8; 95% CI, 1.2-12). None of these six factors was present in 48.3% of the cases and 89% in the controls. A combination of two or more risk factors found to be significant in the univariate analysis showed a pronounced increased risk for seizures (OR = 19; 95% CI, 5.6-65). In the multivariate analysis, the following characteristics remained statistically significant: vaginal bleeding, gestational age, and Cesarean section. Furthermore, smoking also was identified as a risk factor in the multivariate analysis (OR = 3.4; 95% CI, 1.1-10).

CONCLUSIONS

Both pre- and perinatal factors may be associated with later development of epileptic seizures in children. However, in many of the cases, no such factors were identified.

Prognostic factors in the surgical treatment of medically intractable epilepsy associated with mesial temporal sclerosis

OBJECTIVES

To assess the prognostic factors determining seizure remission after temporal lobectomy for intractable epilepsy associated with mesial temporal sclerosis (MTS) at pathology.

METHODS

The clinical and investigative features of 116 consecutive patients who had temporal lobe surgery for drug-resistant epilepsy and MTS at pathology were assessed using actuarial statistics and logistic regression analysis.

RESULTS

At a median follow-up of 63 months the probability of achieving at least a 1-year period of continuous seizure freedom was 67%. Factors contributing to a favourable outcome were interictal EEG localization to the operated lobe and the absence of secondarily generalized seizures. These were also selected in the multivariate analysis, although at lower statistical significance (P=0.08 and 0.09, respectively). Perinatal complications were associated with a significantly worse outcome but overall, complicated febrile convulsions and congruent neuropsychological deficits were not significantly predictive variables.

CONCLUSIONS

The present findings may aid in the non-invasive presurgical assessment of patients with intractable TLE and clinical and neuroimaging evidence of MTS.

Presence of human herpesvirus 6 and herpes simplex virus detected by polymerase chain reaction in surgical tissue from temporal lobe epileptic patients

We investigated the presence of human herpesvirus 6 (HHV-6) and herpes simplex virus (HSV) in surgical tissue from temporal lobe epileptic patients. A total of 17 cases were studied, including eight males and nine females. The mean age was 24.9 +/- 11.1 years and the mean age of onset was 11.1 +/- 5.4 years. Five patients were diagnosed as encephalitis/meningitis and another three had a history of suspected encephalitis/meningitis, but no patient showed any obvious neurological symptom or mental handicap. Mesial and lateral temporal tissues were examined by polymerase chain reaction. Among six patients positive for HHV-6 (35%), the mesial temporal lobe was positive in four and the lateral temporal lobe was positive in three. Herpes simplex virus was positive in only one patient. Three of the six patients positive for HHV-6 did not show any apparent causes. Mild encephalitis/meningitis induced by HHV-6, a condition sometimes not recognized as encephalitis/meningitis, may be one of the most frequent causes of temporal lobe epilepsy.

Pediatric candidates for temporal lobe epilepsy surgery

Temporal lobectomy is an under-valued and effective therapy for selected children with temporal lobe seizures. This article details three components of the identification and evaluation of such children. The ictal symptoms and signs remains an essential component. This includes an aura suggesting limbic system involvement, and the nature of automatisms and other motor phenomena which may have lateralising value. Electroencephalography continues to accurately identify a principally epileptogenic focus in children and adults. The value of high quality magnetic resonance imaging is emphasized. Invasive studies are required in only a minority of cases. Several studies have revealed that 73-100% of carefully selected children receive benefit from this procedure whereas significant neurosurgical complications rarely occur.