Febrile seizures--treatment and outcome

Vaccination and childhood epilepsies

INTRODUCTION

The evidence relating vaccination to febrile seizures and epilepsy is evaluated with an emphasis on febrile seizures (FS), Dravet syndrome (DS), West syndrome, and other developmental and epileptic encephalopathies.

METHODS

A systematic literature review using search words vaccination/immunization AND febrile seizures/epilepsy/Dravet/epileptic encephalopathy/developmental encephalopathy was performed. The role of vaccination as the cause/trigger/aggravation factor for FS or epilepsies and preventive measures were analyzed.

RESULTS

From 1428 results, 846 duplicates and 447 irrelevant articles were eliminated; 120 were analyzed.

CONCLUSIONS

There is no evidence that vaccinations cause epilepsy in healthy populations. Vaccinations do not cause epileptic encephalopathies but may be non-specific triggers to seizures in underlying structural or genetic etiologies. The first seizure in DS may be earlier in vaccinated versus non-vaccinated patients, but developmental outcome is similar in both groups. Children with a personal or family history of FS or epilepsy should receive all routine vaccinations. This recommendation includes DS. The known risks of the infectious diseases prevented by immunization are well established. Vaccination should be deferred in case of acute illness. Acellular pertussis DTaP (diphtheria-tetanus-pertussis) is recommended. The combination of certain vaccine types may increase the risk of febrile seizures however the public health benefit of separating immunizations has not been proven. Measles-containing vaccine should be administered at age 12-15 months. Routine prophylactic antipyretics are not indicated, as there is no evidence of decreased FS risk and they can attenuate the antibody response following vaccination. Prophylactic measures (preventive antipyretic medication) are recommended in DS due to the increased risk of prolonged seizures with fever.

Evaluation of Patients Presenting With First Febrile Seizure

Introduction

Febrile seizure (FS) is the most common cause of convulsion in children. In the present study, we evaluated patients presenting with FS.

Methods

Eighty-two patients aged between 6-60 months who presented to Mersin City Training and Research Hospital with the first febrile seizure between January 2020 and May 2021 were included in the study.

Results

Of the 82 patients included in our study, 42 (51,2%) were male and 40 were female (48,8%). Their average age at presentation of first febrile seizure was 21,05 ± 16,22 months. Fever focus was found in 32 patients (39,1%) with upper respiratory tract infection. Epileptic abnormality was observed in the EEG of six patients (7,3%) and antiepileptic medication was started in three of these patients.

Conclusions

Upper respiratory tract infection, family history of FS, and family history of epilepsy are the main risk factors for the development of FS. Complex FS is a serious risk factor for the development of epilepsy.

Anti-convulsant effects of cultures bear bile powder in febrile seizure via regulation of neurotransmission and inhibition of neuroinflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Natural bear bile powder (NBBP) has been used to treat seizures for thousands of years, but its application is greatly restricted due to ethical reasons. Cultured bear bile powder (CBBP), which is produced by biotransformation, may be an appropriate substitute for NBBP. However, the anti-convulsant effects of CBBP and its mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to investigate the anti-convulsant effects and possible mechanisms of CBBP in a febrile seizure (FS) rat model.

MATERIALS AND METHODS

FS was induced by placing the rats in a warm water bath (45.5 °C). The incidence rate and latency of FS, and hematoxylin-eosin staining (HE) were conducted for neurological damage. The levels of 4 bile acids and 8 main neurotransmitters in vivo were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The expression of bile acid related transports, neurotransmitter receptors, inflammatory factors, neurotrophic factors and glial fibrillary acidic protein (GFAP) in hippocampal tissues were detected by real-time PCR, western blotting, and immunohistochemistry.

RESULTS

Pre-treatments with CBBP and similarly, NBBP, significantly reduced the incidence rate and prolonged the latency of FS. Additionally, CBBP alleviated the histological injury induced by FS in the rat hippocampus tissue. LC-MS/MS analyses revealed that CBBP markedly increased the levels of tauroursodeoxycholic acid (TUDCA), taurochenodeoxycholic acid (TCDCA), ursodeoxycholic acid (UDCA), and chenodeoxycholic acid (CDCA) in FS rats. Furthermore, the content of gamma-aminobutyric acid (GABA) was up-regulated in rats pre-treated with CBBP whereas GFAP was down-regulated. CBBP also significantly suppressed the expression of interleukin -1β (IL-1β), tumor necrosis factor α (TNF-α), nuclear factor kappa B (NF-κB), and brain-derived neurotrophic factor (BDNF) and its TrkB receptors, and improved the expression of GABA type A receptors (GABA_AR) and farnesoid X receptors (FXR).

CONCLUSIONS

The present study demonstrated that CBBP had anti-convulsant effects in a FS rat model. CBBP may protect rats against FS, probably by up-regulating FXR, which was activated by increasing brain bile acids, up-regulating GABAergic transmission by inhibiting BDNF-TrkB signaling, and suppressing neuroinflammation by inhibiting the NF-κB pathway.

Falling admissions to hospital with febrile seizures in the UK

OBJECTIVES

There was a reduction in febrile seizure admissions in Scotland after 2008. Our hypothesis was that a similar trend would be seen in other countries.

METHODS

We obtained the number of febrile and non-febrile seizure admissions in England and Scotland 2000-2013 and the incidence of all seizure admissions 2000-2013 in European countries. We compared the incidence of admission for febrile seizure (Scotland and England) and all seizures (all countries) between 2000-2008 and 2009-2013.

RESULTS

The incidence of febrile seizure admissions per 1000 children in 2009-2013 was lower than 2000-2008 in Scotland (0.79 vs 1.08, p=0.001) and England (0.92 vs 1.20, p<0.001). The incidence of all seizure admissions (but not non-febrile seizures) was lower in 2009-2013 compared with 2000-2008 in Scotland (1.84 vs 2.20, p=0.010) and England (2.71 vs 2.91, p=0.001). Across 12 European countries (including the UK), there was no difference in all seizure admissions after 2008. We explored the possibility that the fall was related to the introduction of routine pneumococcal vaccination in 2006 but there were insufficient data.

CONCLUSION

A fall in admissions for febrile (but not afebrile) seizures after 2008 in Scotland and England explains a fall in all emergency admissions for seizure. A fall in all seizure admissions has not occurred in other European countries, and more research is required to understand the different outcomes in the UK and non-UK countries.

Searsia chirindensis reverses the potentiating effect of prenatal stress on the development of febrile seizures and decreased plasma interleukin-1β levels

It is estimated that more than 80% of patients with epilepsy live in developing countries with 50-60% of them being children. This high prevalence is perpetuated by low socio-economic challenges, poor health care facilities and lack of drug affordability. Searsia chirindensis formerly known as rhus chirindensis and commonly known as 'Red Current' is a popular traditional medicinal plant, which has been used to treat a number of illnesses such as heart complaints and neurological disorders. The aim of this study is to investigate the effects of S. chirindensis on the development of febrile seizure in a prenatally stressed rat. Febrile seizures were induced by administering lipopolysaccharide to 14-day-old rat pups followed by kainic acid. A subset of the rats was treated with Searsia after induction of febrile seizures. Interleukin-1β (IL-1β) levels were measured in plasma. Lipid peroxidation was determined in liver tissue. Our data shows that treatment with Searsia reduced interleukin-1β levels in plasma of the febrile seizure rats and prevented lipid oxidation in the liver. Prenatal stress is dampened by the beneficial effects of Searsia on seizure development in rat pups. These results highlight the potentiating effects of Searsia in the reversal of febrile seizures and prenatal stress effects.

Febrile seizures

Febrile seizure (FS) is the most common seizure disorder of childhood, and occurs in an age-related manner. FS are classified into simple and complex. FS has a multifactorial inheritance, suggesting that both genetic and environmental factors are causative. Various animal models have elucidated the pathophysiological mechanisms of FS. Risk factors for a first FS are a family history of the disorder and a developmental delay. Risk factors for recurrent FS are a family history, age below 18 months at seizure onset, maximum temperature, and duration of fever. Risk factors for subsequent development of epilepsy are neurodevelopmental abnormality and complex FS. Clinicians evaluating children after a simple FS should concentrate on identifying the cause of the child's fever. Meningitis should be considered in the differential diagnosis for any febrile child. A simple FS does not usually require further evaluation such as ordering electroencephalography, neuroimaging, or other studies. Treatment is acute rescue therapy for prolonged FS. Antipyretics are not proven to reduce the recurrence risk for FS. Some evidence shows that both intermittent therapy with oral/rectal diazepam and continuous prophylaxis with oral phenobarbital or valproate are effective in reducing the risk of recurrence, but there is no evidence that these medications reduce the risk of subsequent epilepsy. Vaccine-induced FS is a rare event that does not lead to deleterious outcomes, but could affect patient and physician attitudes toward the safety of vaccination.

Update on the management of simple febrile seizures: emphasis on minimal intervention

PURPOSE OF REVIEW

We summarize recent clinical reviews and updated American Academy of Pediatrics (AAP) clinical guidelines for the management of children with simple febrile seizures.

RECENT FINDINGS

There has been a dramatic reduction in the incidence of bacterial meningitis and of occult bacteremia since the advent of Haemophilus influenzae type b and Streptococcus pneumoniae immunization. This has made routine laboratory evaluation for these bacterial infections unnecessary in a fully immunized, well appearing child who presents with a simple febrile seizure. At the same time there is increasing evidence that the neurotropic human herpes viruses 6 and 7 (HHV-6, HHV-7) comprise a significant proportion of viral infections associated with febrile seizures, and may be the primary cause of the seizure in many instances. Recent evidence-based guidelines emphasize the lack of a need for routine laboratory and neurodiagnostic evaluation, and for prophylactic antipyretics and anticonvulsants, in the majority of children with simple febrile seizures.

SUMMARY

If a child who is fully immunized according to the recommended schedule presents with a simple febrile seizure, minimal intervention should be the norm. Routine blood tests and routine lumbar punctures are usually unnecessary, and the risks of neurodiagnostic procedures (imaging or EEG), prophylactic antipyretics and anticonvulsants far outweigh their potential benefits.

Hyperthermic seizures enhance responsiveness to pentylenetetrazole and induce cognitive dysfunction: protective effect of 3-alkynyl selenophene

AIMS

In this study we investigated the effect of pre-treatment with 3-alkynyl selenophene (3-ASP) against the increase in responsiveness to pentylenetetrazole [PTZ seizure threshold] and cognitive dysfunction induced by experimental febrile seizures (FS). The effects of 3-ASP were compared to those of diazepam (DZP).

MAIN METHODS

Young rats, at postnatal day 21, developed seizures after exposure to a stream of heated air to approximately 41°C. A non-spatial long-term memory and PTZ seizure threshold were determined 30 days after FS. The behavioural seizures were stereotyped followed by facial automatisms, often followed by body flexion. Young rats were pre-treated with 3-ASP (50 and 100mg/kg; per oral route), DZP (1 and 5mg/kg; intraperitoneally) or vehicle.

KEY FINDINGS

3-ASP and DZP pre-treatments were not effective in protecting against seizures induced by FS. 3-ASP pre-treatment protected against the increase in responsiveness to PTZ and cognitive dysfunction induced by FS. DZP pre-treatment was effective in protecting against the increase in responsiveness to PTZ, but not, against the impaired memory induced by FS.

SIGNIFICANCE

3-ASP pre-treatment protected against impairment of memory performance in the step-down passive avoidance task and the increase in the susceptibility to seizures caused by FS early in life of rats.

Frequent fever episodes and the risk of febrile seizures: the Generation R study

AIM

To examine the association between the number of fever episodes and the risk of febrile seizures.

METHODS

This study was embedded in a population-based prospective cohort study from early foetal life onwards. Information about the occurrence of febrile seizures and fever episodes was collected by questionnaires at the ages of 12, 24 and 36 months. Analyses were based on 3033 subjects. The risk of febrile seizures was compared between children with frequent fever episodes (>2 per year), and children with only 1 or 2 fever episodes per year.

RESULTS

The frequency of fever episodes was not associated with the risk of febrile seizures in the age range of 6-12 months. In the second and third year of life, having more than 2 fever episodes was associated with an increased risk of febrile seizures (odds ratios 2.02 [95% confidence interval 1.13-3.62] and 2.29 [95% confidence interval 1.00-5.24], respectively). In the age range between 6 and 36 months, we observed a significant trend between the frequency of fever episodes (<2, 3-4 or >4 per year) and the risk of febrile seizures (p-value for trend < 0.001). The association between the number of fever episodes and the occurrence of febrile seizures was stronger for children with recurrent febrile seizures.

CONCLUSION

Frequent fever episodes are associated with an increased risk of febrile seizures in the second and third years of life. Further studies are needed to identify the mechanisms underlying this association.

Developmental outcome after a single episode of status epilepticus

Consequences of status epilepticus (SE) on psychomotor development and the specific impact of the convulsive event on emerging executive functions remain controversial. Infants treated for a single episode of SE, those treated for a single febrile seizure, and healthy infants were tested with respect to motor development, language, personal, and social skills and self-regulation. The children were divided into two age groups to investigate the impact of the convulsive event at different windows of brain maturation. We found that infants who had had SE were inferior to healthy controls on the development scales. Age differentiated SE impact on visuomotor development versus sociolinguistic development. Children who had been treated for SE had significantly more difficulties delaying a response to an attractive stimulus in one of the long-delay conditions. A single episode of SE can interfere with psychomotor and cognitive development in children without previous developmental delay, and it seems that the functions that are emerging at the time of insult are most vulnerable.

Long-term consequences of a prolonged febrile seizure in a dual pathology model

Clinical evidence suggests that febrile status epilepticus (SE) in children can lead to acute hippocampal injury and subsequent temporal lobe epilepsy. The contribution of febrile SE to the mechanisms underlying temporal lobe epilepsy are however poorly understood. A rat model of temporal lobe epilepsy following hyperthermic SE was previously established in our laboratory, wherein a focal cortical lesion induced at postnatal day 1 (P1), followed by a hyperthermic SE (more than 30 min) at P10, leads to hippocampal atrophy at P22 (dual pathology model) and spontaneous recurrent seizures (SRS) with mild visuospatial memory deficits in adult rats. The goal of this study was to identify the long term electrophysiological, anatomical and molecular changes in this model. Following hyperthermic SE, all cortically lesioned pups developed progressive SRS as adults, characterized by the onset of highly rhythmic activity in the hippocampus. A reduction of hippocampal volume on the side of the lesion preceded the SRS and was associated with a loss of hippocampal neurons, a marked decrease in pyramidal cell spine density, an increase in the hippocampal levels of NMDA receptor NR2A subunit, but no significant change in GABA receptors. These findings suggest that febrile SE in the abnormal brain leads to hippocampal injury that is followed by progressive network reorganization and molecular changes that contribute to the epileptogenesis as well as the observed memory deficits.

Infant febrile seizures: changes in declarative memory as revealed by event-related potentials

OBJECTIVE

According to a widespread opinion the vast majority of infant febrile seizures (IFS) are harmless. However, IFS are often associated with hippocampal sclerosis, which should lead to deficient episodic memory with spared context-free semantic memories. Although IFS represent the most common convulsive disorder in children, these consequences are rarely examined.

METHODS

We measured the hippocampal volume of 17 IFS children (7-9 years old) and an age-matched control group on the basis of MR images. Furthermore, we examined episodic and semantic memory performance with standardized neuropsychological tests. Two processes underlying recognition memory, namely familiarity and recollection, were assessed by means of event-related potentials (ERP).

RESULTS

The IFS children did not show a decreased hippocampus volume. Intelligence, working memory, semantic and episodic memory were intact. However, ERP indices of recognition memory subprocesses revealed deficits in recollection-based remembering that presumably relies on the integrity of the hippocampus, whereas familiarity-based remembering seemed to be intact.

CONCLUSIONS

Although hippocampus volume remains unaffected, IFS seems to induce functional changes in the MTL memory network, characterized by a compensation of recollection by familiarity-based remembering.

SIGNIFICANCE

This study significantly adds to the debate on the consequences of IFS by differentiating the impact on memory processing.

N-methyl-D-aspartate, hyperpolarization-activated cation current (Ih) and gamma-aminobutyric acid conductances govern the risk of epileptogenesis following febrile seizures in rat hippocampus

Febrile seizures are the most common types of seizure in children, and are generally considered to be benign. However, febrile seizures in children with dysgenesis have been associated with the development of temporal lobe epilepsy. We have previously shown in a rat model of dysgenesis (cortical freeze lesion) and hyperthermia-induced seizures that 86% of these animals developed recurrent seizures in adulthood. The cellular changes underlying the increased risk of epileptogenesis in this model are not known. Using whole cell patch-clamp recordings from CA1 hippocampal pyramidal cells, we found a more pronounced increase in excitability in rats with both hyperthermic seizures and dysgenesis than in rats with hyperthermic seizures alone or dysgenesis alone. The change was found to be secondary to an increase in N-methyl-D-aspartate (NMDA) receptor-mediated excitatory postsynaptic currents (EPSCs). Inversely, hyperpolarization-activated cation current was more pronounced in naïve rats with hyperthermic seizures than in rats with dysgenesis and hyperthermic seizures or with dysgenesis alone. The increase in GABAA-mediated inhibition observed was comparable in rats with or without dysgenesis after hyperthermic seizures, whereas no changes were observed in rats with dysgenesis alone. Our work indicates that in this two-hit model, changes in NMDA receptor-mediated EPSCs may facilitate epileptogenesis following febrile seizures. Changes in the hyperpolarization-activated cation currents may represent a protective reaction and act by damping the NMDA receptor-mediated hyperexcitability, rather than converting inhibition into excitation. These findings provide a new hypothesis of cellular changes following hyperthermic seizures in predisposed individuals, and may help in the design of therapeutic strategies to prevent epileptogenesis following prolonged febrile seizures.

Febrile seizures and temporal lobe epileptogenesis

Febrile seizures (FS) are a common neurological disorder that affects children. Simple FS are thought to be benign but experimental and clinical evidence support that the risk of developing epilepsy after FS increases if the FS are prolonged and the brain is abnormal. In addition, prolonged FS (PFS) have many deleterious long-term effects characterized mainly in the hippocampus but may involve the whole brain and that prompt abortive treatment of PFS may prevent some of the adverse effects. This review focuses on some of the key factors involved in the generation of FS, factors leading to PFS and potential mechanisms and functional correlates leading to temporal lobe epilepsy (TLE).

Hippocampal atrophy and abnormal brain development following a prolonged hyperthermic seizure in the immature rat with a focal neocortical lesion

In rats subjected to a focal cortical lesion soon after birth, hyperthermia at P10 induces a prolonged epileptic seizure, often followed by temporal lobe epilepsy in the adult. To determine whether brain damage and notably hippocampal atrophy occur early on in this model, whole brain as well as hemispheric, cortical, subcortical and hippocampal volumes was measured in non-lesioned and lesioned rat pups, 2 days (P12) and 12 days (P22) after the hyperthermic seizure. All pups with a cortical lesion showed reductions in whole brain and in ipsilateral hemispheric, cortical and hippocampal volumes at P12, which persisted at P22 in pups having also sustained a prolonged hyperthermic seizure at P10. Limiting the duration of the seizure with Diazepam prevented the hippocampal atrophy. Thus, a prolonged hyperthermic seizure in immature brain with a subtle neocortical lesion impairs normal brain development, and the duration of the seizure appears to be a key factor in generating hippocampal atrophy.

Hyperthermia-Induced Seizures Modify the GABAA 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.

Febrile convulsions: development and validation of a questionnaire to measure parental knowledge, attitudes, concerns and practices

BACKGROUND

The best medicine for febrile convulsions (FCs) is not prescription medications but effective communication of related information to parents. Therefore, a quick assessment tool for obtaining information about parental responses to FCs is essential for educating parents, clinical practice and research. This paper describes the development and psychometric testing of a questionnaire on parental knowledge, attitudes, concerns and practices (KACP) toward FC.

METHODS

Questionnaire items were created via literature review, interview, and expert consultation. Ten parents were interviewed to develop the questionnaire contents. Nine experts and seven parents were consulted to review the content and face validity of the questionnaire. Of the 326 parents of children with FC visiting 11 emergency departments in southern Taiwan, 216 parents completed the questionnaire, and 64 completed the questionnaire again 2 weeks later. Content validity, internal consistency, test-retest reliability, and item analysis were evaluated.

RESULTS

Cronbach's alpha exceeded 0.72 for the knowledge, attitudes and concerns domains. The item-total correlations in the knowledge and concerns domains ranged from 0.40 to 0.73, but were lower in the attitudes domain (only 4 in 10 items were within 0.40-0.70). The intraclass correlation coefficients (ICC) for the test-retest reliability of the knowledge, attitudes and concerns domains were 0.65, 0.68 and 0.58, respectively. The correlation coefficients between KACP domains were tested and significantly supported the theoretical basis of the questionnaire.

CONCLUSION

For research purposes, the KACP questionnaire measures parental responses with a moderate level of reliability and validity. Cross-cultural investigation of the questionnaire is needed to facilitate its use in other countries.

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.

Febrile seizures in the predisposed brain: A new model of temporal lobe epilepsy

The atypical febrile seizure has important clinical implications because of its association with the mesial temporal lobe epilepsy syndrome, which is the most common of the intractable epilepsies. However, whether a causal relation exists between these conditions is currently unknown. We have previously shown that a focal cortical lesion induced in the neonatal rat predisposes to the development of atypical hyperthermic seizures. We show here that 86% of the lesion plus hyperthermia group experience development of spontaneous recurrent seizures recorded from the amygdala ipsilateral to the lesion. Control rats did not have spontaneous recurrent behavioral or electrographic seizures. Lesioned rats with hyperthermic seizures also showed an impaired performance on the Morris water maze when compared with naive control rats, suggesting mild deficits in learning and memory. These findings support a link between the atypical febrile seizure and mesial temporal lobe epilepsy, and at the same time establish a new model for this condition through which new preventative and therapeutic strategies can be tested.

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.

Parental responses to first and recurrent febrile convulsions

OBJECTIVE

To compare parental knowledge, attitudes, concerns, and first-aid practices for children experiencing febrile convulsions (FC).

SUBJECTS AND METHODS

A questionnaire was mailed to 326 FC parents from 11 emergency departments in southern Taiwan.

RESULTS

A total of 109 first- and 107 recurrent-FC parents responded 1-3 months after the FC. Most incorrectly believed an electroencephalogram (EEG) or computed tomography (CT) was necessary; immunization should be postponed, and overestimated the risk of subsequent epilepsy. Parents were concerned about further attacks in the night, fever episodes, and frequently measured the child's body temperature. During the first episode, objects were inserted into the child's mouth and they were rushed to a hospital. One third lowered the child's body temperature, and 15% positioned the children on their side. For subsequent seizures, 80% anticipated rushing the child to a hospital, and 44% would put objects into the child's mouth. In comparison, although the recurrent-FC parents had higher scores in knowledge and attitudes than the first-FC parents, low knowledge scores (40% correct) were seen in both groups. No significant differences were found on parental concerns, performed/anticipated first aid for FC.

CONCLUSION

Most FC parents had inadequate knowledge, high concerns, and improper first-aid practices. This suggests that parents with either first- or recurrent-FC children need information, emotional support, and first-aid demonstrations.

Is neuronal death required for seizure-induced epileptogenesis in the immature brain?

Do seizures cause neuronal death? At least in the immature hippocampus, this may not be the critical question for determining the mechanisms of epileptogenesis. Neuronal injury and death have clearly been shown to occur in most epilepsy models in the mature brain, and are widely considered a prerequisite to seizure-induced epilepsy. In contrast, little neuronal death occurs after even a severe and prolonged seizure prior to the third postnatal week. However, seizures early in life, for example prolonged experimental febrile seizures, can profoundly and permanently change the hippocampal circuit in a pro-epileptogenic direction. These seizure-induced alterations of limbic excitability may require transient structural injury, but are mainly due to functional changes in expression of gene coding for specific receptors and channels, leading to altered functional properties of hippocampal neurons. Thus, in some pro-epileptogenic models in the developing brain, neither the death of neurons nor death-induced abnormalities of surviving neurons may underlie the formation of an epileptic circuit. Rather, findings in the experimental prolonged febrile seizure model suggest that persistent functional alterations of gene expression ('neuroplasticity') in diverse hippocampal neuronal populations may promote pro-epileptogenic processes induced by these seizures. These findings also suggest that during development, relatively short, intense bursts of neuronal activity may disrupt 'normal' programmed maturational processes to result in permanent, selective alterations of gene expression, with profound functional consequences. Therefore, determining the cascade of changes in the programmed expression of pertinent genes, including their temporal and cell-specific spatial profiles, may provide important information for understanding the process of transformation of an evolving, maturing hippocampal network into one which is hyperexcitable.

Effects of educational intervention on changing parental practices for recurrent febrile convulsions in Taiwan

PURPOSE

To evaluate the effects of educational interventions on parental practices for recurrent febrile convulsions (FC).

METHODS

A 2-year follow-up, nonequivalent comparison group design was used to evaluate the intervention effects. Two educational interventions were provided for FC parents in southern Taiwan. The 326 parents voluntarily chose either to receive a mailed pamphlet (n=196) or to attend a 2-h educational program (n=130). Five telephone interviews focused on investigating FC episodes and parental practices for seizures were conducted at months 3, 6, 12, 18, and 24 after the interventions.

RESULTS

Of the 326 FC children, 78 (23.9%) had recurrent FCs within the 2-year follow-up. Parents who only received pamphlets did not show significant improvements. Parents who attended the educational program demonstrated significant improvements in the recommended practices, particularly in protecting the convulsing child (8.3 vs. 36.1%; p=0.02 by McNemar) and placing the child on his or her side (19.4 vs. 47.2%; p=0.01). Nonrecommended practices including rushing the convulsing child to the hospital (88.9 vs. 30.6%; p < 0.01) and putting protective devices in the child's mouth (38.9 vs. 8.3%; p < 0.01) significantly decreased. By generalized estimating equation analyses, the types of interventions are the single significant factor influencing parental practice changes from initial to recurrent FCs.

CONCLUSIONS

Most parents used inappropriate practices for their child's initial FC. Compared with the mailed pamphlet, the educational program had significant improvements in recommended and nonrecommended practices from initial to recurrent FCs.

The induction of BDNF and c-fos mRNA in the hippocampal formation after febrile seizures

In this study we investigated the expression of brain-derived neurotrophic factor (BDNF) and c-fos mRNA in the hippocampal formation after febrile seizures (FSs) with in situ hybridization histochemistry using riboprobes. The induction of BDNF mRNA was firstly observed in the dentate gyrus at 30 min after FSs. The expression in the dentate gyrus peaked at 3 h and returned to basal level at 24 h. It was also observed in the CA3 of hippocampus from 2 to 3 h. The induction of c-fos mRNA was observed in the dentate gyrus at 30 min and 1 h. These observations suggest that BDNF and c-fos are the genes whose expression can be altered by FSs and might be related to pathologic alterations after FSs.

Assessing risk to benefit ratio in antiepileptic drug therapy

Assessment of risk to benefit ratio in patients with epilepsy is crucial in determining the need for treatment, the choice of drugs and the use of monitoring tools such as laboratory tests and other investigations. Active epilepsy per se carries significant risks in terms of increased mortality, susceptibility to psychopathology and physical injury, and reduced quality of life as a result of restricted lifestyle, stigma and prejudice. By preventing the occurrence of seizures, antiepileptic drugs (AEDs) attenuate or eliminate altogether seizure-related risks, but other risks may arise due to the side effects of the drugs, all of which have a relatively narrow therapeutic index. While there are no major differences in the degree of efficacy between AEDs which are effective in any given seizure type, side effect profiles differ considerably from one agent to another and represent a major factor in determining choice of treatment. Assessment of risk to benefit ratio should also take into consideration patient-specific factors such as type and severity of the epilepsy, age, sex, childbearing potential, medical and drug history, associated disease, use of concomitant medication (including the contraceptive pill) and the prospected patient's compliance. In some benign epilepsy syndromes, such as idiopathic partial epilepsy with centro-temporal spikes, the risk of side effects from AEDs may outweigh potential benefits in terms of seizure control, and treatment is generally not indicated. At the opposite end of the spectrum, the serious morbidity and mortality associated with severe epileptic encephalopathies, such as the Lennox-Gastaut syndrome, justifies aggressive treatment even with drugs associated with a relatively high risk of life threatening side effects such as felbamate. The present article will provide an overview of specific risks associated with epilepsy and with the various drugs used for its treatment, and will attempt to evaluate the complex balance between these risks and therapeutic benefits in different categories of patients.

Febrile seizures: treatment and prognosis

Recent epidemiologic data indicate that the vast majority of children with febrile seizures have a normal longterm outcome. A precise knowledge of the short- and long-term outcome with or without treatment, and short- and long-term side effects is an important prerequisite for assessing the various treatment strategies. We focus on the impact of short-term or prophylactic treatment on the short- and long-term outcome of various types of febrile seizures. There is universal agreement that daily prophylaxis with antiepileptic agents should never be used routinely in simple febrile seizures, but only in highly selected cases, if at all. Intermittent diazepam (DZP) prophylaxis at times of fever may or may not reduce the recurrence rate, but it does not appear to improve the long-term outcome as compared with short-term seizure control. The treatment may be used to reduce the recurrence rate for a small arbitrarily defined group with multiple simple febrile seizures, complex febrile seizures, especially focal, prolonged or both, febrile status, and when parental anxiety is severe. However, there is no evidence that treatment of simple febrile seizures can prevent the rare cases of later epilepsy, and many children with complex febrile seizures have a benign long-term outcome, even without treatment. Many prefer a "wait and see" policy. An attractive alternative is to treat new febrile seizures with rectal DZP in solution at seizure onset, given by the parents at home to prevent febrile status. Newer, less well documented short-term strategies include nasal, oral, or rectal administration of other benzodiazepines. Short-term seizure control of febrile status and careful parental counseling are the two most important targets of treatment.

Genetics of the febrile seizure susceptibility trait

Febrile seizures are the commonest form of convulsion, occurring in 2-5% of infants in Europe and North America and 6-9% of infants in Japan. In large families, the febrile seizure susceptibility trait is inherited by the autosomal dominant pattern with reduced penetrance. In the other families, inheritance appears to be multifactorial. Recent linkage studies provide evidence that regions of chromosomes 8 and 19 contain febrile convulsions (FC) susceptibility genes. This opens up the way to cloning a febrile seizure gene and determining the contributions of these gene loci to febrile seizures in the sporadic cases and the small families. Cloning a febrile seizure gene will make possible new approaches to prevention and therapy. It will also be possible to determine whether a febrile seizure gene contributes to other types of seizures.

Seizure-induced neuronal injury: vulnerability to febrile seizures in an immature rat model

Febrile seizures are the most common seizure type in young children. Whether they induce death of hippocampal and amygdala neurons and consequent limbic (temporal lobe) epilepsy has remained controversial, with conflicting data from prospective and retrospective studies. Using an appropriate-age rat model of febrile seizures, we investigated the acute and chronic effects of hyperthermic seizures on neuronal integrity and survival in the hippocampus and amygdala via molecular and neuroanatomical methods. Hyperthermic seizures-but not hyperthermia alone-resulted in numerous argyrophilic neurons in discrete regions of the limbic system; within 24 hr of seizures, a significant proportion of neurons in the central nucleus of the amygdala and in the hippocampal CA3 and CA1 pyramidal cell layer were affected. These physicochemical alterations of hippocampal and amygdala neurons persisted for at least 2 weeks but were not accompanied by significant DNA fragmentation, as determined by in situ end labeling. By 4 weeks after the seizures, no significant neuronal dropout in these regions was evident. In conclusion, in the immature rat model, hyperthermic seizures lead to profound, yet primarily transient alterations in neuronal structure.

Febrile seizures: genetics and relationship to other epilepsy syndromes

The relationship between febrile seizures and epilepsy has long been debated. We argue that there is some specificity to the types of epilepsy that follow febrile seizures, rather than febrile seizures being a nonspecific marker of a lowered seizure threshold. The relationship between febrile seizures and later epilepsy is frequently genetic. Recent clinical and molecular genetic studies suggest that there are a number of syndrome-specific genes for febrile seizures.