Childhood febrile convulsions--which factors determine the subsequent epilepsy syndrome? A retrospective study

Febrile Seizures, Ongoing Epileptiform Activity, and the Resulting Long-Term Consequences: Lessons From Animal Models

Febrile seizures affect 2% to 14% of children. Prospective studies indicate that following a relatively prolonged febrile seizure there are long-term consequences. Although controlled experiments in children have ethical limitations, nonhuman animal models give us the ability to discover new phenomena, determine their mechanisms, and test treatments that can potentially translate to the human clinical population. Rat models of febrile seizures show two temporally distinct phases: (1); behavioral seizures and (2); ongoing epileptiform activity associated with hyperoxia. The behavioral seizures mimic those displayed by children including tonic-clonic convulsions and loss of postural control. Recordings show classic spiking discharges from cortical regions during the behavioral seizures. Following behavioral seizure termination electrical recordings in rodent models reveal that there is ongoing epileptiform activity that lasts longer than the duration of the behavioral seizures themselves. This ongoing epileptiform activity is also associated with hyperoxia-levels of brain tissue oxygen well above the normoxic zone (typical oxygen levels)-and can last more than an hour. When this hyperoxia, but not the epileptiform activity, is prevented in febrile rat pups the long-term learning impairments are also prevented. This leaves important questions unanswered, "Do children also have ongoing and long-lasting epileptiform activity and associated hyperoxia following termination of their febrile behavioral seizures and does this second phase have long-term consequences"? Here we discuss appropriate animal models of febrile seizures that replicate much of the human condition with special attention to the long-term effects of occult epileptiform activity following termination of a behavioral febrile seizure.

Febrile seizures: A review

Febrile seizures are common, occurring in up to 5% of children in the United States. Frequently perceived by caregivers as a life-threatening event, febrile seizures are a common cause of emergency department visits. The concern for permanent neurologic sequelae and future epilepsy after febrile seizures has resulted in a significant amount of research on these topics. The development of childhood vaccines over the past several decades has led to a significant reduction in childhood bacterial meningitis. This in turn has led to a dramatic change in the evaluation and treatment of febrile seizures. In this review, the different types of febrile seizures as well as the evaluation and prognosis of each are discussed.

Multiple Disruptions of Glial-Neuronal Networks in Epileptogenesis That Follows Prolonged Febrile Seizures

Background and Rationale: Bi-directional neuronal-glial communication is a critical mediator of normal brain function and is disrupted in the epileptic brain. The potential role of aberrant microglia and astrocyte function during epileptogenesis is important because the mediators involved provide tangible targets for intervention and prevention of epilepsy. Glial activation is intrinsically involved in the generation of childhood febrile seizures (FS), and prolonged FS (febrile status epilepticus, FSE) antecede a proportion of adult temporal lobe epilepsy (TLE). Because TLE is often refractory to treatment and accompanied by significant memory and emotional difficulties, we probed the role of disruptions of glial-neuronal networks in the epileptogenesis that follows experimental FSE (eFSE).

Methods: We performed a multi-pronged examination of neuronal-glia communication and the resulting activation of molecular signaling cascades in these cell types following eFSE in immature mice and rats. Specifically, we examined pathways involving cytokines, microRNAs, high mobility group B-1 (HMGB1) and the prostaglandin E2 signaling. We aimed to block epileptogenesis using network-specific interventions as well as via a global anti-inflammatory approach using dexamethasone.

Results: (A) eFSE elicited a strong inflammatory response with rapid and sustained upregulation of pro-inflammatory cytokines. (B) Within minutes of the end of the eFSE, HMGB1 translocated from neuronal nuclei to dendrites, en route to the extracellular space and glial Toll-like receptors. Administration of an HMGB1 blocker to eFSE rat pups did not decrease expression of downstream inflammatory cascades and led to unacceptable side effects. (C) Prolonged seizure-like activity caused overall microRNA-124 (miR-124) levels to plunge in hippocampus and release of this microRNA from neurons via extra-cellular vesicles. (D) Within hours of eFSE, structural astrocyte and microglia activation was associated not only with cytokine production, but also with activation of the PGE₂ cascade. However, administration of TG6-10-1, a blocker of the PGE₂ receptor EP2 had little effect on spike-series provoked by eFSE. (E) In contrast to the failure of selective interventions, a 3-day treatment of eFSE–experiencing rat pups with the broad anti-inflammatory drug dexamethasone attenuated eFSE-provoked pro-epileptogenic EEG changes.

Conclusions: eFSE, a provoker of TLE-like epilepsy in rodents leads to multiple and rapid disruptions of interconnected glial-neuronal networks, with a likely important role in epileptogenesis. The intricate, cell-specific and homeostatic interplays among these networks constitute a serious challenge to effective selective interventions that aim to prevent epilepsy. In contrast, a broad suppression of glial-neuronal dysfunction holds promise for mitigating FSE-induced hyperexcitability and epileptogenesis in experimental models and in humans.

Augmented seizure susceptibility and hippocampal epileptogenesis in a translational mouse model of febrile status epilepticus

OBJECTIVE

Prolonged fever-induced seizures (febrile status epilepticus [FSE]) during early childhood increase the risk for later epilepsy, but the underlying mechanisms are incompletely understood. Experimental FSE (eFSE) in rats successfully models human FSE, recapitulating the resulting epileptogenesis in a subset of affected individuals. However, the powerful viral and genetic tools that may enhance mechanistic insights into epileptogenesis and associated comorbidities, are better-developed for mice. Therefore, we aimed to determine if eFSE could be generated in mice and if it provoked enduring changes in hippocampal-network excitability and the development of spontaneous seizures.

METHODS

We employed C57BL/6J male mice, the strain used most commonly in transgenic manipulations, and examined if early life eFSE could be sustained and if it led to hyperexcitability of hippocampal networks and to epilepsy. Outcome measures included vulnerability to the subsequent administration of the limbic convulsant kainic acid (KA) and the development of spontaneous seizures. In the first mouse cohort, adult naive and eFSE-experiencing mice were exposed to KA. A second cohort of control and eFSE-experiencing young adult mice was implanted with bilateral hippocampal electrodes and recorded using continuous video-electroencephalography (EEG) for 2 to 3 months to examine for spontaneous seizures (epileptogenesis).

RESULTS

Induction of eFSE was feasible and eFSE increased the susceptibility of adult C57BL/6J mice to KA, thereby reducing latency to seizure onset and increasing seizure severity. Of 24 chronically recorded eFSE mice, 4 (16.5%) developed hippocampal epilepsy with a latent period of ~3 months, significantly different from the expectation by chance (P = .04). The limbic epilepsy that followed eFSE was progressive.

SIGNIFICANCE

eFSE promotes pro-epileptogenic network changes in a majority of C57BL/6J male mice and frank "temporal lobe-like" epilepsy in one sixth of the cohort. Mouse eFSE may thus provide a useful tool for investigating molecular, cellular, and circuit changes during the development of temporal lobe epilepsy and its comorbidities.

Myelin water fraction changes in febrile seizures

OBJECTIVE

The objective of this feasibility study was to investigate whether myelin water fraction (MWF) patterns can differentiate children presenting with febrile seizures who will go on to develop nonfebrile epilepsy from those who will not.

PATIENTS AND METHODS

As part of a prospective study of myelination patterns in pediatric epilepsy, seven subjects with febrile seizures underwent magnetic resonance imaging (MRI) including the following standard sequences-T1-weighted, T2-weighted, fluid-attenuated inversion recovery (FLAIR)-and an additional experimental sequence, multicomponent-derived equilibrium single-pulse observation of T1 and T2 (mcDESPOT) to quantify MWF. For each of these subjects, MWF maps were derived and compared with an age-matched population-averaged MWF atlas.

RESULTS

All seven subjects (<5 years old) initially presented with febrile seizures. Of the seven, four had complex seizures and three had simple seizures. All of the children with simple febrile seizures had higher MWF compared with model-derived controls and did not develop epilepsy. All of the children with complex febrile seizures had lower MWF than their model-derived control, and two of these subjects later developed epilepsy.

CONCLUSION

This is the first study in which MWF maps were used to study children with febrile *seizures. This data suggests that relatively higher or stable MWF compared with normative data indicates a lower risk of nonfebrile epilepsy while relatively lower MWF may indicate a pathological condition that could lead to nonfebrile epilepsy.

Trend of subsequent epilepsy in children with recurrent febrile seizures: A retrospective matched cohort study

PURPOSE

Trends of epilepsy in children were correlated with febrile seizure (FS) in a previous retrospective study. In the present study, the authors obtained relevant data from a nationwide cohort database to investigate trends in subsequent epilepsy in children with a history of recurrent FS.

METHODS

A total of 10,210 children with FS comprised the cohort. The diagnosis date was used as the index date. A comparison cohort was randomly matched with each case based on age, sex, urbanization level, parents' occupation, and index date. Cox proportional hazard regression was performed to estimate the hazard ratio and confidence interval of FS-associated epilepsy.

RESULTS

This retrospective cohort study included 7729 children with FS and a comparison cohort of 30,916 children. The incidence of epilepsy was 11.4-fold higher in the FS cohort than in the comparison cohort (5.67 vs. 0.49 per 1000 person-years, respectively). Compared with the comparison cohort, the epilepsy incidence rate ratio increased in children with admissions for FS, from 8.62 at 1 admission to 26.2 at ≥2 admissions (95% CI 6.80-10.9, and 19.78-34.8, respectively; p for trend < 0.0001).

CONCLUSION

FS may increase the risk for subsequent epilepsy in children. Recurrent FS increased the cumulative incidence of epilepsy.

Ischemic-hypoxic mechanisms leading to hippocampal dysfunction as a consequence of status epilepticus

Status epilepticus (SE) is one of the recognized primary precipitating events that can lead to temporal lobe epilepsy (TLE) associated with hippocampal sclerosis. This type of epilepsy is characterized by poor response to drug treatment, often requiring surgical intervention to remove the mesial temporal regions involved in the seizure onset. However, even neurosurgery may not be completely successful. Thus, the prevention of hippocampal damage and epileptogenesis is currently evaluated as a possible alternative therapeutic approach to prevent the development of pharmacoresistant TLE. Lines of evidence suggest that ischemic-hypoxic lesions might occur in different brain regions, including the hippocampus, during SE. Especially in the hippocampal CA3 region, an ischemic-like lesion develops in the stratum lacunosum-moleculare and is mainly characterized by a loss of astrocytes and neuronal processes and increased immunostaining of pimonidazole which probes areas exposed to hypoxia. Interestingly, these mechanisms can contribute to neuronal cell loss and may be counteracted by drugs that can afford vascular protection, as in the case of ligands of the ghrelin receptor. Notably, some of the ghrelin receptor ligands possess a double edge effect, since they are anticonvulsant and vascular-protective, thus, potentially representing new tools to counteract the consequences of SE. This article is part of a Special Issue entitled "Status Epilepticus".

Recent advances in febrile seizures

Febrile seizures are the most common seizures of childhood. A family history of febrile seizures is common, and the disorder is genetically heterogenous. While guidelines are available for management of simple febrile seizures, the management of complex febrile seizures is individualised. After a febrile seizure, it is important to rule out CNS infection and the decision to perform a lumbar puncture should be based on the clinical condition of the child. Neuroimaging and EEG are not required immediately in workup for simple or complex febrile seizures. Recurrence of febrile seizures may be managed at home by the parents with benzodiazepines. If the recurrences are multiple or prolonged and parents are unable to give home treatment, intermittent benzodiazepine prophylaxis may be given. Continuous antiepileptic prophylaxis may be given only to the children where intermittent prophylaxis has failed. Febrile seizures are also associated with increased risk of epilepsy, but this cannot be prevented by any form of treatment. There is also an increased risk of mesial temporal sclerosis, but whether this is an effect or cause of febrile seizures is as yet unclear. There is no increase in neurological handicaps or mortality following febrile seizures.

Early clinical features and diagnosis of Dravet syndrome in 138 Chinese patients with SCN1A mutations

OBJECTIVE

To summarize the early clinical features of Dravet syndrome (DS) patients with SCN1A gene mutations before the age of one.

METHODS

SCN1A gene mutation screening was performed by PCR-DNA sequencing and multiple ligation-dependent probe amplication (MLPA). The early clinical features of DS patients with SCN1A mutations were reviewed with attention to the seizures induced by fever and other precipitating factors before the first year of life.

RESULTS

The clinical data of 138 DS patients with SCN1A gene mutations were reviewed. The median seizure onset age was 5.3 months. Ninety-nine patients (71.7%) experienced seizures with duration more than 15 min in the first year of life. Two or more seizures induced by fever within 24h or the same febrile illness were observed in 93 patients (67.4%). 111 patients (80.4%) had hemi-clonic and (or) focal seizures. Seizures had been triggered by fever of low degree (T<38 °C) in 62.3% (86/138) before the first year of life. Vaccine-related seizures were observed in 34.8% (48/138). Seizures in 22.5% (31/138) of patients were triggered by hot bath. Carbamazepine, oxcarbazepine, lamotrigine, phenobarbital and phenytoin showed either no effect or exacerbating the seizures in our group.

CONCLUSION

The seizure onset age in DS patients was earlier than that was in common febrile seizures. When a baby exhibits two or more features of complex febrile seizures in the first year of life, a diagnosis of DS should be considered, and SCN1A gene mutation screening should be performed as early as possible. Early diagnosis of DS will help clinicians more effectively prescribe antiepileptic drugs for stronger prognosis.

Febrile seizures in rural Tanzania: hospital-based incidence and clinical characteristics

OBJECTIVE

Febrile seizures may contribute to epilepsy later in life, but data in sub-Saharan Africa are scarce. We, therefore, conducted a hospital-based study on clinical characteristics of children with febrile seizures.

METHODS

Over 2 years, we screened all pediatric admissions of Haydom Lutheran Hospital, northern Tanzania, and recruited 197 children with febrile seizures.

RESULTS

The incidence of febrile seizures was 4% of all admitted children aged <10 years, with a mortality of almost 4%. The peak age at the first febrile seizure was 2 years. One of five children experienced repeated episodes, and the majority of children showed features of complex seizures. Approximately 20% of children had a positive family history of febrile seizures or epilepsy.

CONCLUSION

Febrile seizures represent a frequent cause for admission of children, bearing a rather high mortality. Most children exhibit complex febrile seizures, which may contribute to the development of epilepsy later in life.

In vivo MRS and histochemistry of status epilepticus-induced hippocampal pathology in a juvenile model of temporal lobe epilepsy

Childhood status epilepticus (SE) initiates an epileptogenic process that leads to spontaneous seizures and hippocampal pathology characterized by neuronal loss, gliosis and an imbalance between excitatory and inhibitory neurotransmission. It remains unclear whether these changes are a cause or consequence of chronic epilepsy. In this study, in vivo MRS was used in a post-SE juvenile rat model of temporal lobe epilepsy (TLE) to establish the temporal evolution of hippocampal injury and neurotransmitter imbalance. SE was induced in P21 rats by injection of lithium and pilocarpine. Four and eight weeks after SE, in vivo (1) H and γ-aminobutyric acid (GABA)-edited MRS of the hippocampus was performed in combination with dedicated ex vivo immunohistochemistry for the interpretation and validation of MRS findings. MRS showed a 12% decrease (p<0.0001) in N-acetylaspartate and a 15% increase (p=0.0226) in choline-containing compound concentrations, indicating neuronal death and gliosis, respectively. These results were confirmed by FluoroJade and vimentin staining. Furthermore, severe and progressive decreases in GABA (-41%, p<0.001) and glutamate (Glu) (-17%, p<0.001) were found. The specific severity of GABAergic cell death was confirmed by parvalbumin immunoreactivity (-68%, p<0.001). Unexpectedly, we found changes in glutamine (Gln), the metabolic precursor of both GABA and Glu. Gln increased at 4 weeks (+36%, p<0.001), but returned to control levels at 8 weeks. This decrease was consistent with the simultaneous decrease in glutamine synthase immunoreactivity (-32%, p=0.037). In vivo MRS showed gliosis and (predominantly GABAergic) neuronal loss. In addition, an increase in Gln was detected, accompanied by a decrease in glutamine synthase immunoreactivity. This may reflect glutamine synthase downregulation in order to normalize Gln levels. These changes occurred before spontaneous recurrent seizures were present but, by creating a pre-epileptic state, may play a role in epileptogenesis. MRS can be applied in a clinical setting and may be used as a noninvasive tool to monitor the development of TLE.

Outcome of convulsive status epilepticus: a review

The outcome of CSE in childhood depends mainly upon the cause but length of seizure may also be important

Early seizures: causal events or predisposition to adult epilepsy?

Past studies have been unable to confirm whether early seizures predispose to epilepsy in adults. Seizures in infancy were classically thought to cause brain lesions that led to epilepsy in adulthood. However, these infants were not thought to have epilepsy, but acute events that included seizures. Accumulating evidence suggests that early seizures may be associated with, or cause, brain damage; or alternatively, they may be the first expression of a genetic or lesional predisposition to epilepsy. The course of early seizures ranges from transient to life-long, depending on epilepsy syndrome, causes, and treatment. The main factors that determine late or persisting epilepsy after the occurrence of early seizures are protracted seizures, tonic seizures, and involvement of mesial temporal structures. A developmental approach to seizure disorders will aid understanding of epilepsy in adults and improve the design of antiepileptic agents for children and adults.

Febrile seizures

Febrile seizures are the most frequent of seizure disorders in childhood. Febrile seizures are most common in children between 6 months and 3 years of age, with a peak incidence at about 18 months. Approximately 30% to 40% of children who experience a febrile seizure will have a recurrence. The majority of febrile seizures occur within 24 hours of the onset of the fever. Febrile seizures can be simple or complex. Diagnostic studies are usually not necessary. Febrile seizures usually are self-limited, and intervention to stop the seizure often is unnecessary. When possible, the cause of the fever should be treated. Continuous preventative anticonvulsant therapy is not recommended for children with either simple or complex febrile seizures. The use of intermittent anticonvulsant therapy is not routinely indicated. Parental educational and counseling is important. The prognosis is excellent.

Hyperthermia-induced seizures modify the GABA(A) and benzodiazepine receptor binding in immature rat brain

Effects of hyperthermia-induced seizures (HS) on GABA(A) and benzodiazepine (BDZ) receptor binding in immature rat brain were evaluated using in vitro autoradiography. HS were induced in 10-days-old rats by a regulated stream of moderately heated air directed 50 cm above the animals. Rats were killed 30 min, 24 h or 20 days after HS and their brains were used for in vitro autoradiography experiments to determine GABA(A) and BDZ receptor binding. GABA(A) binding was significantly enhanced in all brain areas evaluated 30 min after HS, an effect that endures 24 h and 20 days after seizures. Concerning BDZ receptor binding, a significant increase was detected in entorhinal and perirhinal cortices and decreased in basolateral amygdala 30 min following HS. One day after HS, animals demonstrated enhanced BDZ binding in the cingulate, frontal, posterior parietal, entorhinal, temporal and perirhinal cortices; striatum, accumbens, substantia nigra pars compacta and amygdala nuclei. Twenty days after HS enhanced BDZ binding was restricted in the cingulated, frontal, anterior and posterior parietal cortices, as well as in substantia nigra pars reticulata, whereas decreased values were found in accumbens nucleus and substantia nigra pars compacta. Our data indicate differential effects of HS in GABA(A) and BDZ binding in immature brain. HS-induced GABA(A) and BDZ changes are different from those previously described in experimental models of temporal lobe epilepsy in adult animals.

Increased number of febrile seizures in children born very preterm: relation of neonatal, febrile and epileptic seizures and neurological dysfunction to seizure outcome at 16 years of age

PURPOSE

In prematurely born population, a cascade of events from initial injury in the developing brain to morbidity may be followed. The aim of our study was to assess seizures in prematurely born children from birth up to 16 years and to evaluate the contribution of different seizures, and of neurological dysfunction to the seizure outcome.

METHODS

Pre- and neonatal data and data from neurodevelopmental examination at 5 years of 60 prospectively followed children born at or before 32 weeks of gestation, and of 60 matched term controls from the 2 year birth cohort were available from earlier phases of the study. Later seizure data were obtained from questionnaires at 5, 9, and 16 years, and from hospital records and parent interviews.

RESULTS

In the preterm group, 16 children (27%) exhibited neonatal seizures, 10 children (17%) had seizures during febrile illness and 5 children had epilepsy. Eight children had only febrile seizures, and 3 of these had both multiple simple and complex febrile seizures and neurodevelopmental dysfunction. None of the 8 children had experienced neonatal seizures, 6 had a positive family history of seizures, but none developed epilepsy. The children with epilepsy had CP and neurocognitive problems, and all but one had experienced neonatal seizures; two of them had also had fever-induced epileptic seizures. In controls 3 children (5%) had simple febrile seizures.

CONCLUSION

Children born very preterm have increased rate of febrile seizures compared to the controls. However, no cascade from initial injury via febrile seizures to epilepsy could be shown during the follow-up of 16 years. Symptomatic epilepsy in prematurely born children is characterised by neonatal seizures, major neurological disabilities and early onset of epilepsy.

Outcome of paediatric convulsive status epilepticus: a systematic review

We did a systematic review on the outcome of paediatric convulsive status epilepticus (CSE) and investigated the role of biological and non-biological variables in reported outcomes. The methodological quality of the 63 studies that met our inclusion criteria was assessed. Study design, type of study, and length of follow-up influenced the outcome. The studies with highest methodological quality are associated with better outcome: short-term mortality between 2.7% and 5.2% and morbidity other than epilepsy less than 15%. The incidence of subsequent epilepsy is not increased after cryptogenic CSE. Causal factor is the main determinant of outcome and the effect of age or duration is difficult to separate from the underlying cause. The risk of sequelae in unprovoked and febrile CSE is low. There is some evidence that CSE, especially febrile CSE, might cause hippocampal injury, although its role in the development of mesial temporal sclerosis is unknown.

Hyperthermia-induced seizures modify the GABAA and benzodiazepine receptor binding in immature rat brain

Effects of hyperthermia-induced seizures (HS) on GABAA and benzodiazepine (BDZ) receptor binding in immature rat brain were evaluated using in vitro autoradiography. HS were induced in 10-day-old rats by a regulated stream of moderately heated air directed 50 cm above the animals. Rats were killed 30 min, 24 h, or 20 days after HS and their brains were used for in vitro autoradiography experiments to determine GABAA and BDZ receptor binding. GABAA binding was significantly enhanced in all brain areas evaluated 30 min after HS, an effect that endures 24 h and 20 days after seizures. Concerning BDZ receptor binding, a significant increase was detected in entorhinal and perirhinal cortices and decreased in basolateral amygdala 30 min following HS. One day after HS, animals demonstrated enhanced BDZ binding in the cingulate, frontal, posterior parietal, entorhinal, temporal, and perirhinal cortices; striatum, accumbens, substantia nigra pars compacta, and amygdala nuclei. Twenty days after HS enhanced BDZ binding was restricted in the cingulated, frontal, anterior and posterior parietal cortices, as well as in substantia nigra pars reticulata, whereas decreased values were found in accumbens nucleus and substantia nigra pars compacta. Our data indicate differential effects of HS in GABAA and BDZ binding in immature brain. HS-induced GABAA and BDZ changes are different from those previously described in experimental models of temporal lobe epilepsy in adult animals.

Murine gammaherpesvirus-68 infection of mice: A new model for human cerebral Epstein-Barr virus infection

Epstein-Barr virus infection may cause severe neurological complications that are not mirrored by animal models. Here, we show that nasal inoculation of newborn BALB/c wild-type mice with MHV-68, a murine gammaherpesvirus, causes cerebral infection with inflammation in 50% of the animals. The inflammatory patterns are strikingly similar to those known from Epstein-Barr virus, including hydrocephalus, meningitis, cerebellitis, focal or diffuse encephalitis, and temporal lobe encephalitis. This offers a new powerful tool to study the virological and immunological characteristics of cerebral gammaherpesvirus infections.

Genetic influence on the clinical characteristics and outcome of febrile seizures--a retrospective study

PURPOSE

To assess the influence of the family history (FH) of epilepsy or febrile seizures (FSs) on the clinical presentation of FSs and on their outcome.

METHODS

We reviewed the charts of 482 children admitted to the Ste-Justine Hospital with FSs between 3 months and 6 years of age and followed for at least 5 years.

RESULTS

Children with a positive FH of epilepsy (n=67) showed significantly more focal and recurrent FSs than those without such a FH. The risk of developing partial epilepsy (n=17) or generalized epilepsy (n=19) was significantly greater in children with focal or recurrent FSs, respectively. In children with focal FSs, only two out of 30 (6.7%) children with a negative FH of epilepsy developed partial epilepsy compared with four out of nine (44.4%) children with a positive FH. In children with recurrent FSs, as much as seven out of 34 (20.6%) children with a positive FH of epilepsy developed generalized epilepsy compared to only eight out of 161 (0.05%) of those with a negative FH. Nevertheless, when not taking into account the clinical presentation of FSs, the positive FH of epilepsy constituted a risk factor for developing generalized but not partial epilepsy. Finally, children with a positive FH of FSs (n=120) exhibited significantly more recurrent FSs than those without such a FH, but this did not modify the risk of epilepsy.

CONCLUSION

The FH of FSs and/or epilepsy should be taken into account when evaluating the risk of FSs recurrence and of epilepsy.

In vivo 1H magnetic resonance spectroscopy, T2-weighted and diffusion-weighted MRI during lithium–pilocarpine-induced status epilepticus in the rat

Temporal lobe epilepsy (TLE) is associated with febrile convulsions and childhood status epilepticus (SE). Since the initial precipitating injury, triggering epileptogenesis, occurs during this SE, we aimed to examine the metabolic and morphological cerebral changes during the acute phase of experimental SE noninvasively. In the rat lithium-pilocarpine model of SE, we performed quantified T(2)- and isotropic-diffusion-weighted (DW) magnetic resonance imaging (MRI) at 3 and 5 h of SE and acquired single-voxel (1)H MR spectra at 2, 4 and 6 h of SE. T(2) was globally decreased, most pronounced in the amygdala (Am) and piriformic cortex (Pi), in which also a significant decrease in apparent diffusion coefficient (ADC) was found. In contrast, ADC values increased transiently in the hippocampus (HC) and thalamus (Th). MR spectra showed a decrease in N-acetylaspartate (NAA) and choline (Cho) and an increase of lactate in a hippocampal voxel. The T(2) decrease, attributed to raised deoxyhemoglobin, and the presence of lactate both indicate a mismatch between oxygen demand and delivery. The ADC decrease, indicative of excitotoxicity, confirms that the amygdala and piriformic cortex are particularly vulnerable to lithium-pilocarpine-induced seizures. The transient ADC increase in the thalamus may reflect the breakdown of the blood-brain barrier (BBB), which is shown to occur in this region at these time points. Neuronal damage and failure of energy-dependent formation of NAA are likely causes of an observed decrease in NAA, while the decrease in Cho is possibly due to depletion of the cholinergic system. This study illustrates that relative hypoxia, excitotoxicity and concomitant neuronal damage associated with SE can be probed noninvasively with MR. These pathological phenomena are the first to contribute to the pathophysiology of spontaneous recurrent seizures in a later stage in this animal model.

Febrile seizures: an update

This review focuses on the latest knowledge and understanding of febrile seizures and outlines the more important issues in the management of children who present with an apparent "febrile seizure". It is not the remit of this paper to discuss the detailed management of febrile seizures. Throughout this review, the words "partial" and "focal" will be used interchangeably and the term "febrile seizure" (FS) will be used, reflecting the proposed changes in the terminology of seizures and epilepsies.1