Febrile seizures: current views and investigations

Evaluation of Febrile Seizures Focusing on the Diurnal Variation

Background and objectives Several studies have reported the diurnal variation of febrile seizures (FS) in children. However, it remains unclear whether there is a difference in diurnal variation depending on the types of FS. The present study aims to investigate whether simple FS or complex FS influences diurnal fluctuations. Methods In this single-facility retrospective study, Japanese pediatricians collected clinical data from 247 children with FS. We evaluated the diurnal occurrence of FS using medical files. The Kolmogorov-Smirnov test was used to assess differences in distribution by classifying days into four six-hour time periods: night (0:00-6:00), morning (6:00-12:00), afternoon (12:00-18:00), and evening (18:00-24:00). Results In the simple FS group, the highest rate was observed in the evening (35.16%), followed by the afternoon (29.69%), with the lowest rate in the morning (14.06%). In the complex FS group, the highest rates were observed in both the afternoon (30.95%) and evening (30.95%), with the lowest rate at night (16.67%). The distributions of simple FS and complex FS were significantly different. Conclusion FS exhibited different diurnal variations depending on the type of FS. Clinicians' recognition of these findings will aid in treatment.

Seizures in febrile children with SARS-CoV-2 infection: clinical features, short-term follow-up

BACKGROUND

As the Omicron variant of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) emerges, the neurological manifestations correlated with this epidemic have garnered increasing attention. This study was primarily intended to compare seizures in febrile children with and without SARS-CoV-2 infection and to conduct short-term follow-up of the SARS-CoV-2-infected patients.

METHODS

Retrospective analysis of patients admitted to the Children's Hospital of Chongqing Medical University for fever and seizures between October 1 and December 30, 2022. Based on the results of SARS-CoV-2 Reverse Transcription-Polymerase Chain Reaction(RT-PCR) at the time of admission, the patients were divided into a Coronavirus disease 2019(COVID-19) positive group and a COVID-19 negative group. Aside from that, we followed up COVID-19-positive patients for 3 months after their discharge from the hospital. The follow-up included monitoring for post-discharge seizures.

RESULTS

Compared with the COVID-19-negative group, the COVID-19-positive group had a higher proportion of seizure duration ≥ 15 min(18.7%VS5.1%;P = 0.001), seizure ≥ 2 time(54.4%VS41.0%; P = 0.024), status epilepticus(15.4%VS5.1%; P = 0.005), and Electroencephalogram (EEG) abnormalities(29.4%VS13.6%; P = 0.016). Among the 161 individuals under follow-up, 21 (13.0%)experienced a recurrence of seizures.

CONCLUSIONS

Although the incidence of seizure duration ≥ 15 min, number of seizures ≥ 2 time, and status epilepticus was higher in the COVID-19-positive group, the majority of patients had a favorable prognosis. Nonetheless, patients with COVID-19 who present with seizures and persistent impaired consciousness need to be alerted to serious neurological disorders such as acute necrotizing encephalopathy. Owing to the consideration that some patients may experience a recurrence of seizures within a short period of time, it is paramount to provide guardians with education about the emergency management of seizures and to follow up with patients over time.

Feeding metformin during pregnancy and lactation periods improved learning and memory impairment in the rat offspring exposed to febrile seizure: Role of oxidative stress and inflammatory response

BACKGROUND

Many clinical evidences have reported the higher risk of seizure in young children and infants after exposure to hyperthermia, which more likely can cause brain damage and affect cognitive function, so, many researches were focused on prevention or treatment of febrile seizure (FS) with minimal adverse effects. Considering the potential effects of oxidative stress as a prominent trigger in FS, and demonstrating the anti-oxidant effects of metformin, the present study aimed to investigate the protective effect of metformin administration in prenatal and lactation periods in rat pups exposed to hyperthermia by which induced seizure.

METHOD AND MATERIALS

Pregnant rats were divided into six groups: (1) vehicle: pregnant rats received normal saline during pregnancy and lactation; (2) FS: pregnant rats received normal saline during pregnancy and lactation; (3-5) FS-Met50/100/150 mg/kg: pregnant rats received different doses of metformin including 50, 100 and 150 mg/kg during pregnancy and lactation; (6) Met150 mg/kg: pregnant rats received Met150 mg/kg during pregnancy and lactation. The male pups born to mothers received in all FS groups exposed to hyperthermia. All experimental groups were allowed to grow up, and after the lactation period, they were subjected for behavioural tests and biochemical analysis.

RESULTS

According to the present findings, the prenatal and lactation exposure to the highest dose of metformin demonstrated significant difference with FS group in both behavioural and biochemical test analyses. Although the remaining doses of metformin were also effective, the much better results were reported with the highest dose of metformin (150 mg/kg). Interestingly, the highest dose of metformin administered alone demonstrated better result than vehicle in probe trial test.

CONCLUSION

Considering the present research and related study in relation to metformin in ameliorating the epilepsy symptoms, there are numerous evidences on positive effect of metformin on seizure. Although the exact mechanism is unclear, the anti-oxidant effect of metformin is strongly supported.

Alterations in Seizure Frequency in Patients with Epilepsy Following Coronavirus Disease 2019

Background and Purpose

During the coronavirus disease 19 (COVID-19) pandemic, a considerable number of studies have focused on the difficulties for accessing the medical services and telemedicine-related issues. However, it is not clear whether COVID-19 affects the clinical course of epilepsy. Therefore, in the current study we aimed to assess the effects of COVID-19 infection on seizure frequency in patients with epilepsy (PWE).

Methods

We evaluated PWE who consecutively referred to the neurology clinics of 22 Bahman and Qaem hospitals, who had experienced a recent polymerase chain reaction-confirmed-COVID-19 infection. Data were collected through a pre-defined electronic questionnaire.

Results

A total of 104 patients were included. Females represented 52% of the population. The mean age of the patients was 36.73±17.87. Thirty-six patients (34%) reported increased seizure frequency. The mean age of the patients who had exacerbated seizure frequency was significantly lower than the non-exacerbated group (27.50±9.8 vs. 40.14±18.39; p=0.005). The number of the male patients were significantly higher in the exacerbated group (52% vs. 25%; p=0.014). The majority of exacerbated group had a history of drug resistance (44.4% vs. 8.5%; p=0.022). The number of epileptic seizures before COVID-19 infection was higher in the exacerbated (p=0.04).

Conclusions

About 34% of PWE experienced exacerbated epileptic seizures after COVID-19 infection. Male patients, young patients, patients with the history of drug resistance, and the patients who had higher seizure frequency were at increased risk for seizure exacerbation. Our results highlight the importance of screening, early diagnosis, and treatment in PWE.

A dynamics model of neuron-astrocyte network accounting for febrile seizures

Febrile seizure (FS) is a full-body convulsion caused by a high body temperature that affect young kids, however, how these most common of human seizures are generated by fever has not been known. One common observation is that cortical neurons become overexcited with abnormal running of sodium and potassium ions cross membrane in raised body temperature condition, Considering that astrocyte Kir4.1 channel play a critical role in maintaining extracellular homeostasis of ionic concentrations and electrochemical potentials of neurons by fast depletion of extracellular potassium ions, we examined here the potential role of temperature-dependent Kir4.1 channel in astrocytes in causing FS. We first built up a temperature-dependent computational model of the Kir4.1 channel in astrocytes and validated with experiments. We have then built up a neuron-astrocyte network and examine the role of the Kir4.1 channel in modulating neuronal firing dynamics as temperature increase. The numerical experiment demonstrated that the Kir4.1 channel function optimally in the body temperature around 37 °C in cleaning 'excessive' extracellular potassium ions during neuronal firing process, however, higher temperature deteriorates its cleaning function, while lower temperature slows down its cleaning efficiency. With the increase of temperature, neurons go through different stages of spiking dynamics from spontaneous slow oscillations, to tonic spiking, fast bursting oscillations, and eventually epileptic bursting. Thus, our study may provide a potential new mechanism that febrile seizures may be happened due to temperature-dependent functional disorders of Kir4.1 channel in astrocytes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11571-021-09706-w.

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.

How does the COVID-19 cause seizure and epilepsy in patients? The potential mechanisms

The new coronavirus has spread throughout the world in a very short time and now has become a pandemic. Most infected people have symptoms such as dry cough, dyspnea, tiredness, and fever. However, the Covid-19 infection disrupts various organs, including the liver, kidney, and nervous system. Common neurological symptoms of the Covid-19 infection include delirium, confusion, headache, and loss of sense of smell and taste. In rare cases it can cause stroke and epilepsy. The virus enters the nervous system either directly through nerve pathways or indirectly through the ACE2 receptor. The neurological symptoms of a Covid-19 infection in the brain are mainly due to either the entry of pro-inflammatory cytokines into the nervous system or the production of these cytokines by microglia and astrocytes. Pro-inflammatory cytokines can cause blood-brain barrier disruption, increase in glutamate and aspartate and reduce GABA levels, impairs the function of ion channels, and finally, high levels of cytokines can cause epilepsy. Understanding the potential mechanisms is necessary to gain better insight into COVID-19 induced seizure pathogenesis and to design the correct treatment strategies to achieve appropriate treatment for seizure and epilepsy.

Dexamethasone Attenuates Hyperexcitability Provoked by Experimental Febrile Status Epilepticus

The role of neuroinflammation in the mechanisms of epilepsy development is important because inflammatory mediators provide tractable targets for intervention. Inflammation is intrinsically involved in the generation of childhood febrile seizures (FSs), and prolonged FS [febrile status epilepticus (FSE)] precedes a large proportion of adult cases of temporal lobe epilepsy (TLE). As TLE is often refractory to therapy and is associated with serious cognitive and emotional problems, we investigated whether its development can be prevented using anti-inflammatory strategies. Using an immature rat model of FSE [experimental FSE (eFSE)], we administered dexamethasone (DEX), a broad anti-inflammatory agent, over 3 d following eFSE. We assessed eFSE-provoked hippocampal network hyperexcitability by quantifying the presence, frequency, and duration of hippocampal spike series, as these precede and herald the development of TLE-like epilepsy. We tested whether eFSE provoked hippocampal microgliosis, astrocytosis, and proinflammatory cytokine production in male and female rats and investigated blood–brain barrier (BBB) breaches as a potential contributor. We then evaluated whether DEX attenuated these eFSE sequelae. Spike series were not observed in control rats given vehicle or DEX, but occurred in 41.6% of eFSE-vehicle rats, associated with BBB leakage and elevated hippocampal cytokines. eFSE did not induce astrocytosis or microgliosis but provoked BBB disruption in 60% of animals. DEX significantly reduced spike series prevalence (to 7.6%) and frequency, and abrogated eFSE-induced cytokine production and BBB leakage (to 20%). These findings suggest that a short, postinsult intervention with a clinically available anti-inflammatory agent potently attenuates epilepsy-predicting hippocampal hyperexcitability, potentially by minimizing BBB disruption and related neuroinflammation.

Differential roles of NaV1.2 and NaV1.6 in regulating neuronal excitability at febrile temperature and distinct contributions to febrile seizures

Dysregulation of voltage-gated sodium channels (VGSCs) is associated with multiple clinical disorders, including febrile seizures (FS). The contribution of different sodium channel subtypes to environmentally triggered seizures is not well understood. Here we demonstrate that somatic and axonal sodium channels primarily mediated through Na_V1.2 and Na_V1.6 subtypes, respectively, behave differentially at FT, and might play distinct roles in FS generation. In contrast to sodium channels on the main axonal trunk, somatic ones are more resistant to inactivation and display significantly augmented currents, faster gating rates and kinetics of recovery from inactivation at FT, features that promote neuronal excitabilities. Pharmacological inhibition of Na_V1.2 by Phrixotoxin-3 (PTx3) suppressed FT-induced neuronal hyperexcitability in brain slice, while up-regulation of Na_V1.2 as in Na_V1.6 knockout mice showed an opposite effect. Consistently, Na_V1.6 knockout mice were more susceptible to FS, exhibiting much lower temperature threshold and shorter onset latency than wildtype mice. Neuron modeling further suggests that Na_V1.2 is the major subtype mediating FT-induced neuronal hyperexcitability, and predicts potential outcomes of alterations in sodium channel subtype composition. Together, these data reveal a role of native Na_V1.2 on neuronal excitability at FT and its important contribution to FS pathogenesis.

Fever and hypothermia in systemic inflammation

Systemic inflammation-associated syndromes (e.g., sepsis and septic shock) often have high mortality and remain a challenge in emergency medicine. Systemic inflammation is usually accompanied by changes in body temperature: fever or hypothermia. In animal studies, systemic inflammation is often modeled by administering bacterial lipopolysaccharide, which triggers autonomic and behavioral thermoeffector responses and causes either fever or hypothermia, depending on the dose and ambient temperature. Fever and hypothermia are regulated changes of body temperature, which correspond to mild and severe forms of systemic inflammation, respectively. Mediators of fever and hypothermia are called endogenous pyrogens and cryogens; they are produced when the innate immune system recognizes an infectious pathogen. Upon an inflammatory challenge, hepatic and pulmonary macrophages (and later brain endothelial cells) start to release lipid mediators, of which prostaglandin (PG) E₂ plays the key role, and cytokines. Blood PGE₂ enters the brain and triggers fever. At later stages of fever, PGE₂ synthesized within the blood-brain barrier maintains fever. In both cases, PGE₂ is synthesized by cyclooxygenase-2 and microsomal PGE₂synthase-1. Mediators of hypothermia are not well established. Both fever and hypothermia are beneficial host defense responses. Based on evidence from studies in laboratory animals and clinical trials in humans, fever is beneficial for fighting mild infection. Based mainly on animal studies, hypothermia is beneficial in severe systemic inflammation and infection.

Cytokine cascades induced by mechanical trauma injury alter voltage-gated sodium channel activity in intact cortical neurons

BACKGROUND

Traumatic brain injury (TBI) triggers both immediate (primary) and long-term (secondary) tissue damages. Secondary damages can last from hours to days or even a lifetime. Secondary damages implicate several mechanisms, including influence of inflammatory mediators, mainly cytokines, on excitability of ion channels. However, studies should further explore the effects of inflammatory cytokines on voltage-gated sodium channels (VGSCs) and excitability in distal intact neurons.

METHODS

Mixed cultures of mouse cortical astrocytes and neurons were subjected to mechanical injury (trauma) to mimic TBI in vitro. Expression of various cytokines in these cultures were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assay. A trauma-conditioned medium with or without brain-derived neurotrophic factor (BDNF) was added to mouse primary cortical neurons for 6 and 24 h to mimic combined effects of multiple inflammatory cytokines on VGSCs. Spike behaviors of distal intact neurons were examined by whole-cell patch-clamp recordings.

RESULTS

Mechanical injury in mixed cortical neuron-astrocyte cultures significantly increased expression levels of multiple cytokines, including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, monocyte chemoattractant protein-1, chemokine (C-C motif) ligand-5, IL-10, and transforming growth factor-β1, at 6 and 24 h after injury. Incubation in trauma-conditioned medium increased functional VGSCs in neuronal membranes and Na⁺ currents. Enhanced VGSCs were almost completely abolished by BDNF, and reinforcement of Na⁺ currents was also reduced in a dose-dependent manner. BDNF (30 ng/mL) also significantly reversed reduced neuronal cell viability, which was induced by medium conditioned at 6 h. At 6 and 24 h, trauma-conditioned medium significantly increased spike frequency but not spike threshold.

CONCLUSIONS

In TBI, the combined effect of inflammatory cytokines is directly involved in VGSC, Na⁺ current, and excitability dysfunction in distal intact neurons. BDNF may partly exert neuroprotective effects by maintaining balance of VGSC function in distal intact neurons.

Behavioral fever in ectothermic vertebrates

Fever is an evolutionary conserved defense mechanism which is present in both endothermic and ectothermic vertebrates. Ectotherms in response to infection can increase their body temperature by moving to warmer places. This process is known as behavioral fever. In this review, we summarize the current knowledge on the mechanisms of induction of fever in mammals. We further discuss the evolutionary conserved mechanisms existing between fever of mammals and behavioral fever of ectothermic vertebrates. Finally, the experimental evidences supporting an adaptive value of behavioral fever expressed by ectothermic vertebrates are summarized.

Systemic features of rotavirus infection

A growing body of evidence warrants a revision of the received/conventional wisdom of rotavirus infection as synonymous with acute gastroenteritis. Rotavirus vaccines have boosted our interest and knowledge of this virus, but also importantly, they may have changed the landscape of the disease. Extraintestinal spread of rotavirus is well documented, and the clinical spectrum of the disease is widening. Furthermore, the positive impact of current rotavirus vaccines in reducing seizure hospitalization rates should prompt a reassessment of the actual burden of extraintestinal manifestations of rotavirus diseases. This article discusses current knowledge of the systemic extraintestinal manifestations of rotavirus infection and their underlying mechanisms, and aims to pave the way for future clinical, public health and research questions.

Na (+) /Ca (2+) Exchanger 3 is Downregulated in the Hippocampus and Cerebrocortex of Rats with Hyperthermia-induced Convulsion

BACKGROUND

Na + /Ca 2+ exchanger (NCX) plays a crucial role in pentylenetetrazol-induced convulsion. However, it is unclear whether NCX is critically involved in hyperthermia-induced convulsion. In this study, we examined the potential changes in NCX3 in the hippocampus and cerebrocortex of rats with hyperthermia-induced convulsion.

METHODS

Twenty-one Sprague Dawley rats were randomly assigned to control group, convulsion-prone group and convulsion-resistant group (n = 7 in each group). Whole-cell patch-clamp method was used to record NCX currents. Both the Western blotting analysis and immunofluorescence labeling techniques were used to examine the expression of NCX3.

RESULTS

NCX currents were decreased in rats after febrile convulsion. Compared to the control group, NCX3 expression was decreased by about 40% and 50% in the hippocampus and cerebrocortex of convulsion-prone rats, respectively. Furthermore, the extent of reduction in NCX3 expression seemed to correlate with the number of seizures.

CONCLUSIONS

There is a significant reduction in NCX3 expression in rats with febrile convulsions. Our findings also indicate a potential link between NCX3 expression, febrile convulsion in early childhood, and adult onset of epilepsy.

Fever and sickness behavior: Friend or foe?

Fever has been recognized as an important symptom of disease since ancient times. For many years, fever was treated as a putative life-threatening phenomenon. More recently, it has been recognized as an important part of the body's defense mechanisms; indeed at times it has even been used as a therapeutic agent. The knowledge of the functional role of the central nervous system in the genesis of fever has greatly improved over the last decade. It is clear that the febrile process, which develops in the sick individual, is just one of many brain-controlled sickness symptoms. Not only will the sick individual appear "feverish" but they may also display a range of behavioral changes, such as anorexia, fatigue, loss of interest in usual daily activities, social withdrawal, listlessness or malaise, hyperalgesia, sleep disturbances and cognitive dysfunction, collectively termed "sickness behavior". In this review we consider the issue of whether fever and sickness behaviors are friend or foe during: a critical illness, the common cold or influenza, in pregnancy and in the newborn. Deciding whether these sickness responses are beneficial or harmful will very much shape our approach to the use of antipyretics during illness.

Incidence of febrile seizure in patients with Down syndrome

BACKGROUND

It is unclear whether the incidence of febrile seizure (FS) in children with Down syndrome (DS) is higher or lower than in the general population. In this study, we investigated the incidence of FS in DS patients using mailed questionnaires.

METHODS

The questionnaires were distributed to parents or caregivers of DS patients attending Osaka Medical College Hospital and six other facilities. The questionnaires were returned by mail from February 2012 to September 2013 from 323 families of DS patients (176 male, 147 female; age range, 3 months-47 years; median age, 5.0 years). To assess the incidence of FS in DS, we performed the following two analyses: (i) we calculated the incidence of FS among DS patients between the ages of 4 and 20 years (n = 199; 113 male, 86 female), and (ii) we extracted families with both DS and healthy siblings between the ages of 4 and 20 years (n = 150; 77 male, 73 female) and compared the incidence of FS in these sibling groups.

RESULTS

Five DS patients had a past history of FS. The incidence of FS in DS was 2.5%. The incidence of FS was significantly lower in DS patients compared with healthy siblings (P < 0.003; OR, 0.14).

CONCLUSION

The incidence of FS is lower in DS patients than in the general population.

Mechanisms of fever production and lysis: lessons from experimental LPS fever

Fever is a cardinal symptom of infectious or inflammatory insults, but it can also arise from noninfectious causes. The fever-inducing agent that has been used most frequently in experimental studies designed to characterize the physiological, immunological and neuroendocrine processes and to identify the neuronal circuits that underlie the manifestation of the febrile response is lipopolysaccharide (LPS). Our knowledge of the mechanisms of fever production and lysis is largely based on this model. Fever is usually initiated in the periphery of the challenged host by the immediate activation of the innate immune system by LPS, specifically of the complement (C) cascade and Toll-like receptors. The first results in the immediate generation of the C component C5a and the subsequent rapid production of prostaglandin E2 (PGE2). The second, occurring after some delay, induces the further production of PGE2 by induction of its synthesizing enzymes and transcription and translation of proinflammatory cytokines. The Kupffer cells (Kc) of the liver seem to be essential for these initial processes. The subsequent transfer of the pyrogenic message from the periphery to the brain is achieved by neuronal and humoral mechanisms. These pathways subserve the genesis of early (neuronal signals) and late (humoral signals) phases of the characteristically biphasic febrile response to LPS. During the course of fever, counterinflammatory factors, "endogenous antipyretics," are elaborated peripherally and centrally to limit fever in strength and duration. The multiple interacting pro- and antipyretic signals and their mechanistic effects that underlie endotoxic fever are the subjects of this review.

Impact of Rotavirus Vaccination on Childhood Hospitalization for Seizures

BACKGROUND

Rotavirus vaccine (RV) might reduce the risk of hospitalization due to childhood seizures (CS). We aimed to identify and assess variations in the incidence of hospitalizations for CS among children <5 years of age before and after RV introduction.

METHODS

Annual hospitalization rates for any kind of CS, before and after RV introduction in 2007, were calculated using the official surveillance system for hospitalization data.

RESULTS

Our study cohort totaled 6149 children <5 years of age admitted to the hospital between 2003 and 2013 with any kind of CS (780.3* + 779.0* + 333.2* + 345* ICD-9-CM code). The annual hospitalization rates for any kind of CS in children <5 years of age were correlated with RV coverage (r = -0.673; P = 0.033) and rotavirus acute gastroenteritis admission rates (ρ = 0.506; P = 0.001), with decrease rates ranging from 16.2% (95% confidence interval: 8.3-23.5%) in 2007 to 34.0% (27.3-40.1%) in 2010, as compared with the median rate of the pre-vaccination period (2003 to 2006). Similarly, for convulsions (780.3*ICD-9-CM code), the decrease seen in children <5 years of age was significantly correlated with the increase in RV coverage (r = -0.747; P = 0.013) and rotavirus acute gastroenteritis admission rates (ρ = 0.543; P < 0.001), with decrease rates ranging from 18.7% (9.6-26.8%) in 2007 to 42.5% (35.3-48.9%) in 2012. Significant results were also obtained for infants <12 months and infants 1-2 years of age. In the remaining age groups or diagnostic categories analyzed, changes were either not significant or not related to vaccination changes or rotavirus acute gastroenteritis admission rates.

CONCLUSIONS

Our results show that rotavirus vaccination may have a significant impact in the decrease in seizure-related hospitalizations in childhood. This additional benefit of rotavirus vaccination seems more marked in the youngest infants.

Visualization of different characteristics of cerebrospinal fluid with acute encephalopathy and febrile seizures using pattern recognition analysis of 1H NMR

BACKGROUND

In acute encephalopathy, deterioration of the condition can be rapid, and early intervention is essential to prevent progression of the disease. However, in the acute period, differentiating acute encephalopathy from febrile seizures is difficult. Thus, an early diagnostic marker has been sought to enable early intervention. Proton nuclear magnetic resonance ((1)H NMR) spectroscopy is used to study the chemical characteristics of biological fluids such as cerebrospinal fluid (CSF). The purpose of this study was to ascertain if pattern recognition of (1)H NMR spectra could differentiate CSF obtained from patients with acute encephalopathy and febrile seizures.

METHODS

CSF was obtained from patients with acute encephalopathy (n = 4), complex febrile seizures (n = 9), and simple febrile seizures (n = 9).

RESULTS

NMR spectra of CSF did not visually differ across the three groups. Spectral data were analyzed by partial least squares discriminant analysis and visualized by plotting the partial least squares scores of each sample. The three patient groups clustered separately on the plots.

CONCLUSION

In this preliminary study, we were able to visualize different characteristics of CSF obtained from patients with acute encephalopathy and simple and complex febrile seizures using pattern recognition analysis of (1)H NMR data.

The anti-seizure drugs vinpocetine and carbamazepine, but not valproic acid, reduce inflammatory IL-1β and TNF-α expression in rat hippocampus

In the present study, the effects of the two classical anti-epileptic drugs, carbamazepine and valproic acid, and the non-classical anti-seizure drug vinpocetine were investigated on the expression of the pro-inflammatory cytokines IL-1β and TNF-α in the hippocampus of rats by PCR or western blot after the administration of one or seven doses. Next, the effects of the anti-seizure drugs were investigated on the rise in cytokine expression induced by lipopolysaccharides (LPS) inoculation in vivo. To validate our methods, the changes induced by the pro-convulsive agents 4-aminopyridine, pentylenetetrazole and pilocarpine were also tested. Finally, the effect of the anti-seizure drugs on seizures and on the concomitant rise in pro-inflammatory cytokine expression induced by 4-aminopyridine was explored. Results show that vinpocetine and carbamazepine reduced the expression of IL-1β and TNF-α from basal conditions, and the increase in both pro-inflammatory cytokines induced by LPS. In contrast, valproic acid failed to reduce both the expression of the cytokines from basal conditions and the rise in IL-1β and TNF-α expression induced by LPS. Tonic-clonic seizures induced either by 4-aminopyridine, pentylenetetrazole or pilocarpine increased the expression of IL-1β and TNF-α markedly. 4-aminopyridine-induced changes were reduced by all the tested anti-seizure drugs, although valproic acid was less effective. We conclude that the anti-seizure drugs, vinpocetine and carbamazepine, whose mechanisms of action involve a decrease in ion channels permeability, also reduce cerebral inflammation. The mechanism of action of anti-seizure drugs like vinpocetine and carbamazepine involves a decrease in Na(+) channels permeability. We here propose that this mechanism of action also involves a decrease in cerebral inflammation.

GABAA receptor biogenesis is impaired by the γ2 subunit febrile seizure-associated mutation, GABRG2(R177G)

A missense mutation in the GABAA receptor γ2L subunit, R177G, was reported in a family with complex febrile seizures (FS). To gain insight into the mechanistic basis for these genetic seizures, we explored how the R177G mutation altered the properties of recombinant α1β2γ2L GABAA receptors expressed in HEK293T cells. Using a combination of electrophysiology, flow cytometry, and immunoblotting, we found that the R177G mutation decreased GABA-evoked whole-cell current amplitudes by decreasing cell surface expression of α1β2γ2L receptors. This loss of receptor surface expression resulted from endoplasmic reticulum (ER) retention of mutant γ2L(R177G) subunits, which unlike wild-type γ2L subunits, were degraded by ER-associated degradation (ERAD). Interestingly, when compared to the condition of homozygous γ2L(R177G) subunit expression, disproportionately low levels of γ2L(R177G) subunits reached the cell surface with heterozygous expression, indicating that wild-type γ2L subunits possessed a competitive advantage over mutant γ2L(R177G) subunits for receptor assembly and/or forward trafficking. Inhibiting protein synthesis with cycloheximide demonstrated that the R177G mutation primarily decreased the stability of an intracellular pool of unassembled γ2L subunits, suggesting that the mutant γ2L(R177G) subunits competed poorly with wild-type γ2L subunits due to impaired subunit folding and/or oligomerization. Molecular modeling confirmed that the R177G mutation could disrupt intrasubunit salt bridges, thereby destabilizing secondary and tertiary structure of γ2L(R177G) subunits. These findings support an emerging body of literature implicating defects in GABAA receptor biogenesis in the pathogenesis of genetic epilepsies (GEs) and FS.

Febrile seizures: recent developments and unanswered questions

BACKGROUND

Febrile seizures (FS) are typically observed in infants and children affecting 2-5 % of the pediatric population and are the commonest seizures in childhood.

OBJECTIVES

The present review summarizes epidemiology, etiology, clinical picture, and diagnostic procedures as well as the therapeutic options and the different courses this disorder may take.

METHOD

An extensive review of literature is performed, while views and aspects towards the pathogenesis of FS are stated. Risk factors for multiple recurrences of FS and for subsequent epilepsy are analyzed. Questions regarding the treatment and follow-up of children with FS are answered.

RESULTS

Whereas the frequency of epilepsy following simple FS is estimated to be 1.0-2.2 % of patients, and thus does not differ from the risk of normal population, complicated FS are associated with an increased risk of subsequent epilepsy in 4.1-6.0 %. Febrile status epilepticus with focal symptoms may result in approximately 5 % of cases in complex partial epilepsy. Furthermore, multiple recurrences increase the risk for generalized epilepsy (>4 %). The immediate management of FS, intermittent prophylaxis, and the effectiveness of the treatment in combination with antipyretics are presented in detail.

CONCLUSION

FS can cause a great anxiety and even panic to parents and to the whole family. Parents should be educated about the benign condition and the good prognosis. Although much information has been gained, much remains to be learned.

High-frequency EEG oscillations in hyperthermia-induced seizures of Scn1a mutant rats

We examined high-frequency oscillations (HFOs) in the ictal cortical EEGs of hyperthermia-induced seizures in a rat model of febrile seizures with an SCN1A mutation as a means of investigating the pathophysiological mechanisms underlying the generation of febrile seizures. We used 13 male homozygous Scn1a-N1417H mutant rats (F344/NSlc-Scn1a(Kyo811)) and 10 wild-type control rats. Generalized tonic-clonic seizures were induced in all mutant rats, and HFOs with frequencies ranging from 200 to 400 Hz were found to precede spikes during the clonic phases of these seizures in the ictal EEGs. The proportion of all spikes in each seizure that were associated with HFOs increased with age. In time-frequency spectra of the EEG data, the HFOs had a mean peak frequency of 301.1 ± 65.4 Hz (range: 156.3-468.8Hz) and a mean peak power of 24.6 ± 3.8 dB (range: 11.4-33.4 dB); the peak power increased with age. Regarding the wild-type rats, a brief seizure without unmistakable HFOs was exceptionally induced in only one rat. The generation mechanism of febrile seizures is still an unanswered question. The detection of HFOs from the ictal EEGs of hyperthermia-induced seizures may provide a cue to answering this open question, although in this research we were unable to provide sufficient evidence to prove that the generation of HFOs depended on the mutation.

Stress sensitivity of childhood epilepsy is related to experienced negative life events

PURPOSE

To evaluate the effect of stress on seizure frequency in childhood epilepsy, and to assess possible differences between children in whom seizures are precipitated by stress and those in whom they are not.

METHODS

Parents or caregivers of children with active epilepsy (aged 2-16 years) were sent questionnaires on developmental and epilepsy characteristics, life-time stress exposure, and the effect of stressful periods and moments of acute stress on seizure frequency in their child. Further information was extracted from patient files.

KEY FINDINGS

Parents or caregivers of 153 children with a median age of 8.8 years responded to the questionnaires. Thirty-nine percent reported an increase in seizure frequency during periods of stress, with a median increase of 2.5 times the frequency compared to nonstressful periods. Thirty-seven percent reported that seizures were precipitated by acute stress, with stress being a precipitating factor in 33% (median value) of the seizures. Overall, 51% of the patients reported stress sensitivity of seizures. A higher number of negative life events experienced in total life was related to an increase in seizure frequency in stressful periods (odds ratio [OR] 1.3, p = 0.01) as well as to the precipitation of seizures by acute stress (OR 1.3, p = 0.02).

SIGNIFICANCE

Stress sensitivity is reported in half of the children with epilepsy. Results of this study suggest a relation between experienced negative life events and stress sensitivity of childhood epilepsy. One possible explanation could be that experiencing negative life events may cause a larger response to daily stressors, thereby increasing the likelihood to induce epileptic activity.

Measles-containing vaccines and febrile seizures in children age 4 to 6 years

BACKGROUND

In the United States, children receive 2 doses of measles-mumps-rubella vaccine (MMR) and varicella vaccine (V), the first between ages 1 to 2 years and the second between ages 4 to 6 years. Among 1- to 2-year-olds, the risk of febrile seizures 7 to 10 days after MMRV is double that after separate MMR + V. Whether MMRV or MMR + V affects risk for febrile seizure risk among 4- to 6-year-olds has not been reported.

METHODS

Among 4- to 6-year-old Vaccine Safety Datalink members, we identified seizures in the emergency department and hospital from 2000 to 2008 and outpatient visits for fever from 2006 to 2008 during days 7 to 10 and 0 to 42 after MMRV and MMR + V. Incorporating medical record reviews, we assessed seizure risk after MMRV and MMR + V.

RESULTS

From 2006 through 2008, 86 750 children received MMRV; from 2000 through 2008, 67 438 received same-day MMR + V. Seizures were rare throughout days 0 to 42 without peaking during days 7 to 10. There was 1 febrile seizure 7 to 10 days after MMRV and 0 after MMR + V. Febrile seizure risk was 1 per 86 750 MMRV doses (95% confidence interval, 1 per 3 426 441, 1 per 15 570) and 0 per 67 438 MMR + V doses (1 per 18 282).

CONCLUSIONS

This study provides reassurance that MMRV and MMR + V were not associated with increased risk of febrile seizures among 4- to 6-year-olds. We can rule out with 95% confidence a risk greater than 1 febrile seizure per 15 500 MMRV doses and 1 per 18 000 MMR + V doses.

Cytokines and brain excitability

Cytokines are molecules secreted by peripheral immune cells, microglia, astrocytes and neurons in the central nervous system. Peripheral or central inflammation is characterized by an upregulation of cytokines and their receptors in the brain. Emerging evidence indicates that pro-inflammatory cytokines modulate brain excitability. Findings from both the clinical literature and from in vivo and in vitro laboratory studies suggest that cytokines can increase seizure susceptibility and may be involved in epileptogenesis. Cellular mechanisms that underlie these effects include upregulation of excitatory glutamatergic transmission and downregulation of inhibitory GABAergic transmission.

Epilepsy and brain inflammation

During the last decade, experimental research has demonstrated a prominent role of glial cells, activated in brain by various injuries, in the mechanisms of seizure precipitation and recurrence. In particular, alterations in the phenotype and function of activated astrocytes and microglial cells have been described in experimental and human epileptic tissue, including modifications in potassium and water channels, alterations of glutamine/glutamate cycle, changes in glutamate receptor expression and transporters, release of neuromodulatory molecules (e.g. gliotransmitters, neurotrophic factors), and induction of molecules involved in inflammatory processes (e.g. cytokines, chemokines, prostaglandins, complement factors, cell adhesion molecules) (Seifert et al., 2006; Vezzani et al., 2011; Wetherington et al., 2008). In particular, brain injury or proconvulsant events can activate microglia and astrocytes to release a number of proinflammatory mediators, thus initiating a cascade of inflammatory processes in brain tissue. Proinflammatory molecules can alter neuronal excitability and affect the physiological functions of glia by paracrine or autocrine actions, thus perturbing the glioneuronal communications. In experimental models, these changes contribute to decreasing the threshold to seizures and may compromise neuronal survival (Riazi et al., 2010; Vezzani et al., 2008). In this context, understanding which are the soluble mediators and the molecular mechanisms crucially involved in glio-neuronal interactions is instrumental to shed light on how brain inflammation may contribute to neuronal hyperexcitability in epilepsy. This review will report the clinical observations in drug-resistant human epilepsies and the experimental findings in adult and immature rodents linking brain inflammation to the epileptic process in a causal and reciprocal manner. By confronting the clinical evidence with the experimental findings, we will discuss the role of specific soluble inflammatory mediators in the etiopathogenesis of seizures, reporting evidence for both their acute and long term effects on seizure threshold. The possible contribution of these mediators to co-morbidities often described in epilepsy patients will be also discussed. Finally, we will report on the anti-inflammatory treatments with anticonvulsant actions in experimental models highlighting possible therapeutic options for treating drug-resistant seizures and for prevention of epileptogenesis.

Evaluation of candidate genes from orphan FEB and GEFS+ loci by analysis of human brain gene expression atlases

Febrile seizures, or febrile convulsions (FEB), represent the most common form of childhood seizures and are believed to be influenced by variations in several susceptibility genes. Most of the associated loci, however, remain ‘orphan’, i.e. the susceptibility genes they contain still remain to be identified. Further orphan loci have been mapped for a related disorder, genetic (generalized) epilepsy with febrile seizures plus (GEFS+).

We show that both spatially mapped and ‘traditional’ gene expression data from the human brain can be successfully employed to predict the most promising candidate genes for FEB and GEFS+, apply our prediction method to the remaining orphan loci and discuss the validity of the predictions. For several of the orphan FEB/GEFS+ loci we propose excellent, and not always obvious, candidates for mutation screening in order to aid in gaining a better understanding of the genetic origin of the susceptibility to seizures.

Is neuronal death necessary for acquired epileptogenesis in the immature brain?

A central question concerning acquired epileptogenesis in the immature brain is whether neuronal death is required for the development of epilepsy after a brain insult. Results from three different animal models of brain injury during early development have been used to develop the hypothesis that status epilepticus, prolonged febrile seizures, or hypoxia-induced seizures can lead to chronic epilepsy without the occurrence of neuronal death. This brief review will summarize the evidence supporting the hypothesis in each model and then critique the data and published interpretations. A case will be made that the evidence to date neither rules out the occurrence of neuronal death nor demonstrates that epileptogenesis (i.e., spontaneous recurrent seizures) has actually occurred in these animal models of acquired pediatric epilepsy. We also review evidence for the opposing hypothesis: acquired epileptogenesis in the immature brain requires, or at least often involves, neuronal death.

Epileptogenesis after prolonged febrile seizures: mechanisms, biomarkers and therapeutic opportunities

Epidemiological and recent prospective analyses of long febrile seizures (FS) and febrile status epilepticus (FSE) support the idea that in some children, such seizures can provoke temporal lobe epilepsy (TLE). Because of the high prevalence of these seizures, if epilepsy was to arise as their direct consequence, this would constitute a significant clinical problem. Here we discuss these issues, and describe the use of animal models of prolonged FS and of FSE to address the following questions: Are long FS epileptogenic? What governs this epileptogenesis? What are the mechanisms? Are there any predictive biomarkers of the epileptogenic process, and can these be utilized, together with information about the mechanisms of epileptogenesis, for eventual prevention of the TLE that results from long FS and FSE.

Does acquired epileptogenesis in the immature brain require neuronal death

Because epilepsy often occurs during development, understanding the mechanisms by which this process takes place (epileptogenesis) is important. In addition, the age-specificity of seizures and epilepsies of the neonatal, infancy, and childhood periods suggests that the processes and mechanisms that culminate in epilepsy might be age specific as well. Here we provide an updated review of recent and existing literature and discuss evidence that neuronal loss may occur during epileptogenesis in the developing brain, but is not required for the epileptogenic process. We speculate about the mechanisms for the resilience of neurons in immature limbic structures to epileptogenic insults, and propose that the type, duration and severity of these insults influence the phenomenology of the resulting spontaneous seizures.