Volumetric magnetic resonance imaging differences between complex febrile seizure and recurrent simple febrile seizure

PURPOSE

We investigated the volumetric differences in cortical and subcortical structures between patients with complex febrile seizure (FS) and recurrent simple FS. We aimed to identify the brain morphological patterns of children with complex FS.

METHODS

Twenty-five patients with complex FS and age- and sex-matched 25 patients with recurrent simple FS with structural magnetic resonance imaging (MRI) scans were studied. Cortical volumetric analysis was performed using a voxel-based morphometry method with the CAT12 toolbox within SPM12. FSL-FIRST was used to obtain volume measures of subcortical deep grey matter structures (amygdala, caudate nucleus, thalamus, nucleus accumbens, putamen, globus pallidus, and hippocampus). The volumetric asymmetry index (AI) and laterality index (LI) were calculated for each subcortical structure.

RESULTS

Compared with recurrent simple FS, complex FS demonstrated lower volume in the left putamen (p = .003) and right nucleus accumbens (p = .001). Additionally, patients with complex FS presented a higher magnitude of AI of the nucleus accumbens (p < .001) compared with recurrent simple FS.

CONCLUSIONS

The findings indicate that volumetric analysis may be a useful marker for the detection of FS-induced changes that reflect microstructural alterations. This study is the first to report on alterations in the putamen and nucleus accumbens in FS.

Febrile Seizure Causes Deficit in Social Novelty, Gliosis, and Proinflammatory Cytokine Response in the Hippocampal CA2 Region in Rats

Febrile seizure (FS), which occurs as a response to fever, is the most common seizure that occurs in infants and young children. FS is usually accompanied by diverse neuropsychiatric symptoms, including impaired social behaviors; however, research on neuropsychiatric disorders and hippocampal inflammatory changes following febrile seizure occurrences is very limited. Here, we provide evidence linking FS occurrence with ASD pathogenesis in rats. We developed an FS juvenile rats model and found ASD-like abnormal behaviors including deficits in social novelty, repetitive behaviors, and hyperlocomotion. In addition, FS model juvenile rats showed enhanced levels of gliosis and inflammation in the hippocampal CA2 region and cerebellum. Furthermore, abnormal levels of social and repetitive behaviors persisted in adults FS model rats. These findings suggest that the inflammatory response triggered by febrile seizures in young children could potentially serve as a mediator of social cognitive impairments.

Clinical characteristics of MRI-negative temporal lobe epilepsy

PURPOSE

To investigate the characteristics of patients with MRI-negative temporal lobe epilepsy (TLE) (1.5 T brain MRI) in comparison with: (i) patients with hippocampal sclerosis (HS)-TLE; (ii) persons with non-HS structural TLE; and (iii) patients with dual pathology.

METHODS

This was a retrospective study. All patients with an electro-clinical diagnosis of TLE were studied at the outpatient epilepsy clinic at Shiraz University of Medical Sciences, Shiraz, Iran, from 2008 until 2020.

RESULTS

Six hundred and forty-one patients were studied [273 (42.6%) HS, 154 (24.0%) non-HS structural TLE, 174 (27.1%) MRI-negative TLE, and 40 (6.2%) dual pathology]. The groups differed significantly. Important dissimilarities included: (i) compared with HS-TLE group, patients with MRI-negative TLE more often had a family history of epilepsy and less often had a history of febrile convulsion; (ii) compared with non-HS structural TLE group, patients with MRI-negative TLE more often had focal to bilateral tonic-clonic seizures, less often had focal seizures with impaired awareness, and more often had a family history of epilepsy; (iii) compared with the dual pathology group, patients with MRI-negative TLE less often were male and less often had a history of febrile convulsion.

CONCLUSION

Patients with MRI-negative TLE are not a homogenous group of people and it is not necessarily a distinct entity from other forms of TLE either. With the emergence of advanced imaging technologies, the underlying pathologies of MRI-negative TLE may be revealed.

Acute Phase Serum Leptin, Adiponectin, Interleukin-6, and Visfatin Are Altered in Chinese Children With Febrile Seizures: A Cross-Sectional Study

Adipokines, including leptin, visfatin, adiponectin, and interleukin-6 (IL)-6, play multiple roles in the pathophysiology of epilepsy and febrile seizures (FS). We aimed to investigate the associations among plasma adipokines, mainly leptin, visfatin, adiponectin, or IL-6, and the prognosis of FS. This prospective cross-sectional study was conducted from January 2017 to December 2018 at the Wuxi Second People' Hospital China. The levels of serum leptin, visfatin, adiponectin, and IL-6 in 55 children with FS (FS group) were compared with 42 febrile children without seizure (FC group) and 48 healthy children (HC group) in an acute phase. The correlation with clinical indicators was determined by logistic regression analysis. Serum adiponectin and IL-6 levels were significantly higher in the FS group than in the FC and HC groups (p < 0.05), but there was no statistical difference between the FC and HC groups. In addition, logistic regression analysis showed that high concentrations of adiponectin and IL-6 were significantly associated with the occurrence of FS. For leptin and visfatin, they were significantly lower in the FS and FC groups than in the normal control group, but there was no statistical difference between the FS and FC groups. Our results suggest that higher plasma levels of IL-6 and adiponectin may serve as an additional biomarker in the early treatment or follow-up of the FS children.

Novel Inflammatory Neuropathology in Immature Brain: (1) Fetal Tuberous Sclerosis, (2) Febrile Seizures, (3) α-B-crystallin, and (4) Role of Astrocytes

Though the term "inflammation" is traditionally defined as proliferation or infiltration of lymphatic cells of the lymphatic immune system and macrophages or as immunoreactive proteins including cytokines, interleukins and major histocompatibility complexes, recently recognized reactions to tissue injury also are inflammation, often occurring in the central nervous system in conditions where they previously were not anticipated and where they may play a role in both pathogenesis and repair. We highlight 4 such novel inflammatory conditions revealed by neuropathologic studies: (1) inflammatory markers and cells in the brain of human fetuses with tuberous sclerosis complex and perhaps other disorders of the mechanistic target of rapamycin genetic or metabolic pathway, (2) inflammatory markers in the brain related to febrile seizures of infancy and early childhood, (3) heat-shock protein upregulation in glial cells and neurons at sites of chronic epileptic foci, and (4) the emerging role of astrocytes in the presence of and participation in inflammation. Novel evidence shows that cerebral inflammation plays a role in some genetic diseases as early as midgestation and thus is not always acquired postnatally or in adult life.

Increased interleukin-1β and basic fibroblast growth factor levels in the cerebrospinal fluid during human herpesvirus-6B (HHV-6B) encephalitis

Human herpesvirus 6B (HHV-6B) causes exanthema subitum in infants and is known to be mildly pathogenic. However, HHV-6B infection can induce febrile seizures in a high percentage of patients, and in rare cases, result in encephalitis. We detected higher levels of interleukin (IL)-1β and basic fibroblast growth factor (bFGF) in the cerebrospinal fluid (CFS) of patients with HHV-6B encephalitis when compared to those in patients with non-HHV-6B-induced febrile seizures. In vitro, IL-1β and bFGF enhanced HHV-6B gene expression in infected U373 astrocytes during the initial and maintenance phases of infection, respectively. These findings indicated that IL-1β and bFGF contribute to HHV-6B growth and the onset of encephalitis.

Clinical Profile and Electroencephalogram Findings in Children with Seizure Presenting to Dhulikhel Hospital

Background Seizure disorder is the most common childhood neurologic condition and a major public health concern. Identification of the underlying seizure etiology helps to identify appropriate treatment options and the prognosis for the child. Objective This study was conducted to investigate the clinical profile, causes and electroencephalogram findings in children with seizure presenting to a tertiary center in Kavre district. Method This was a hospital based prospective study carried out in the Department of Pediatrics, Dhulikhel Hospital, Kavre from 1st April 2015 to 31st March 2016. Variables collected were demographics, clinical presentations, laboratory tests, brain imaging studies, electroencephalography, diagnosis and outcome. Result Study included 120 (age 1 month to 16 years) children attending Dhulikhel Hospital. Majority of the patients were male (60.84%). Age at first seizure was less than 5 years in 75.83% of children. Seizure was generalized in 62.50%, focal in 31.67% and unclassified in 5.83%. Common causes of seizure were - Primary generalized epilepsy (26.66%), neurocysticercosis (10%) and hypoxic injury (6.6%) which was diagnosed in the perinatal period. Febrile seizure (26.66%) was the most common cause of seizure in children between 6 months to 5 years of age. Neurological examination, electroencephalography and Computed Tomography were abnormal in 71.66%, 68.92% and 58.14% cases respectively. Seizure was controlled by monotherapy in 69.16% cases and was resistant in 7.50% of the cases. Conclusion Primary generalized epilepsy and febrile seizure were the most common causes of seizures in children attending Dhulikhel Hospital. Electroencephalogram findings help to know the pattern of neuronal activity. Response to monotherapy was good and valproic acid was the most commonly used drug.

Experimental febrile seizures impair interastrocytic gap junction coupling in juvenile mice

Prolonged and focal febrile seizures (FSs) have been associated with the development of temporal lobe epilepsy (TLE), although the underlying mechanism and the contribution of predisposing risk factors are still poorly understood. Using a kainate model of TLE, we previously provided strong evidence that interruption of astrocyte gap junction-mediated intercellular communication represents a crucial event in epileptogenesis. To elucidate this aspect further, we induced seizures in immature mice by hyperthermia (HT) to study the consequences of FSs on the hippocampal astrocytic network. Changes in interastrocytic coupling were assessed by tracer diffusion studies in acute slices from mice 5 days after experimental FS induction. The results reveal that HT-induced FSs cause a pronounced reduction of astrocyte gap junctional coupling in the hippocampus by more than 50%. Western blot analysis indicated that reduced connexin43 protein expression and/or changes in the phosphorylation status account for this astrocyte dysfunction. Remarkably, uncoupling occurred in the absence of neuronal death and reactive gliosis. These data provide a mechanistic link between FSs and the subsequent development of TLE and further strengthen the emerging view that astrocytes have a central role in the pathogenesis of this disorder. © 2016 Wiley Periodicals, Inc.

Reducing premature KCC2 expression rescues seizure susceptibility and spine morphology in atypical febrile seizures

Atypical febrile seizures are considered a risk factor for epilepsy onset and cognitive impairments later in life. Patients with temporal lobe epilepsy and a history of atypical febrile seizures often carry a cortical malformation. This association has led to the hypothesis that the presence of a cortical dysplasia exacerbates febrile seizures in infancy, in turn increasing the risk for neurological sequelae. The mechanisms linking these events are currently poorly understood. Potassium-chloride cotransporter KCC2 affects several aspects of neuronal circuit development and function, by modulating GABAergic transmission and excitatory synapse formation. Recent data suggest that KCC2 downregulation contributes to seizure generation in the epileptic adult brain, but its role in the developing brain is still controversial. In a rodent model of atypical febrile seizures, combining a cortical dysplasia and hyperthermia-induced seizures (LHS rats), we found a premature and sustained increase in KCC2 protein levels, accompanied by a negative shift of the reversal potential of GABA. In parallel, we observed a significant reduction in dendritic spine size and mEPSC amplitude in CA1 pyramidal neurons, accompanied by spatial memory deficits. To investigate whether KCC2 premature overexpression plays a role in seizure susceptibility and synaptic alterations, we reduced KCC2 expression selectively in hippocampal pyramidal neurons by in utero electroporation of shRNA. Remarkably, KCC2 shRNA-electroporated LHS rats show reduced hyperthermia-induced seizure susceptibility, while dendritic spine size deficits were rescued. Our findings demonstrate that KCC2 overexpression in a compromised developing brain increases febrile seizure susceptibility and contribute to dendritic spine alterations.

Hydrogen Sulfide Promotes Learning and Memory and Suppresses Proinflammatory Cytokines in Repetitive Febrile Seizures

OBJECTIVE

Hydrogen sulfide (H2S), as a novel gasotransmitter, plays important roles in a number of physiological and pathological processes. Its effectiveness has been demonstrated in different types of brain disorders but not in repetitive febrile seizure (febrile status epilepticus; FSE) models. This study aims to test whether a donor of H2S sodium sulfhydrate (NaHS) is also effective for FSE in rats.

METHODS

FSE was induced in rat pups on postnatal day 10 in water at 45.0 ± 0.1°C for 10 consecutive days with or without preadministration of NaHS. Following evaluation of the latency and duration of hyperthermic seizures, impairment in learning and memory was measured by the Morris water maze test. Moreover, alterations of the microglial response and the production of proinflammatory cytokines IL-1β and TNF-α were calculated in the hippocampus.

RESULTS

We found that NaHS significantly increased the latency and decreased the duration of hyperthermic seizures. Furthermore, NaHS-treated pups showed less impairment in learning and memory. In addition, NaHS inhibited FSE-induced microglial responses and suppressed the production of IL-1β and TNF-α in the hippocampus.

CONCLUSION

NaHS appears to be effective for the treatment of FSE in infants and children, in part due to its anti-inflammatory action.

Analysis of safety data in children after receiving two doses of ProQuad® (MMRV)

BACKGROUND

In randomized clinical studies, over 11,800 children, 12 months to 6 years of age, were administered ProQuad(®), a combination measles, mumps, rubella, and varicella vaccine (MMRV). This paper describes the safety following a 2-dose regimen of MMRV administered to children in the second year of life.

METHODS

Safety data from five clinical studies were combined for all children who were scheduled to receive two doses of MMRV ∼3-6 months apart. All vaccinated children were followed for safety following each dose of MMRV.

RESULTS

Of 3112 children who received a first dose of MMRV, 2780 (89.3%) received a second dose of MMRV. Overall, 70.5% and 57.7% of children reported ≥1 adverse experiences following first and second doses of MMRV, respectively. Injection-site redness was statistically significantly higher postdose 2 than postdose 1, while injection-site pain/tenderness was statistically significantly higher postdose 1 compared to postdose 2. Rashes were statistically significantly lower postdose 2 compared to postdose 1. Ten febrile seizures (8 postdose 1, 2 postdose 2) were reported following MMRV vaccination. The incidence of febrile seizures postdose 1 of MMRV was 0.26% (8/3019) compared to 0.07% (2/2695) postdose 2 of MMRV.

CONCLUSIONS

Administration of two doses of MMRV has an acceptable safety profile in children 12 to 23 months of age. There is a small increase in the risk of febrile seizures following the first dose of MMRV as compared to the component vaccines, but the risk for any individual child is relatively low.

Postnatal interleukin-1β enhances adulthood seizure susceptibility and neuronal cell death after prolonged experimental febrile seizures in infantile rats

Febrile seizures (FS) are recognized as an antecedent to the development of temporal lobe epilepsy with hippocampal sclerosis (TLE-HS), but it is unclear whether prolonged FS are a direct cause of TLE-HS. Here, we used a rat model of infantile FS to study the effects of inflammatory cytokines on seizure susceptibility and neuronal death in adults. Prolonged hyperthermia-induced seizures (pHS) were induced in male Lewis rats at post natal day (P) 10. Cytokines were administered twice intranasally, once immediately after pHS and once the following day. The effects of intranasal interleukin (IL)-1β or tumor necrosis factor (TNF) α were tested in rats undergoing a single episode of pHS (P10) and in rats undergoing repeated pHS (P10 and P12). Seizure susceptibility was tested at P70-73 by quantifying the seizure onset time (SOT) after kainic acid administration, and neuronal cell injury and gliosis in adulthood. SOT significantly reduced in rats receiving IL-1β together with repeated pHS, whereas no significant effects were seen in rats receiving IL-1β after a single pHS episode, or in rats receiving TNFα. Hippocampal neuronal cell loss was observed in the CA3 region of rats receiving IL-1β together with repeated pHS; however, there was no significant change in gliosis among each group. Our results are consistent with the hypothesis that excessive production of IL-1β after repeated prolonged FS can enhance adult seizure susceptibility and neuronal cell death, and might contribute to the development of TLE-HS.

Genetic background of febrile seizures

Febrile seizures (FSs) occur in children older than 1 month and without prior afebrile seizures in the absence of a central nervous system infection or acute electrolyte imbalance. Their pathogenesis is multifactorial. The most relevant familial studies evidence an occurrence rate ranging from 10% to 46% and median recurrence rate of 36% in children with positive familial history for FS. The main twin studies demonstrated a higher concordance rate in monozygotic twins with FS than in dizygotic ones. Linkage studies have proposed 11 chromosomal locations responsible to FS attributed to FEB1 to FEB11. Population-based association studies have shown at least one positive association for 14 of 41 investigated genes with FS. The proinflammatory cytokine interleukin 1β (IL-1β) was the most investigated and also gene associated with susceptibility to FS. A possible role in the overlapping of epilepsy and FS was found for 16 of 36 investigated genes. SCN1A, IL-1β, CHRNA4, and GABRG2 were the most commonly involved genes in this context. The genetic background of FS involves the regulation of different processes, including individual and familial susceptibility, modulation of immune response, and neuronal excitability and interactions with exogenous agents such as viruses.

Novel HCN2 mutation contributes to febrile seizures by shifting the channel's kinetics in a temperature-dependent manner

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channel-mediated currents, known as I h, are involved in the control of rhythmic activity in neuronal circuits and in determining neuronal properties including the resting membrane potential. Recent studies have shown that HCN channels play a role in seizure susceptibility and in absence and limbic epilepsy including temporal lobe epilepsy following long febrile seizures (FS). This study focused on the potential contributions of abnormalities in the HCN2 isoform and their role in FS. A novel heterozygous missense mutation in HCN2 exon 1 leading to p.S126L was identified in two unrelated patients with FS. The mutation was inherited from the mother who had suffered from FS in a pedigree. To determine the effect of this substitution we conducted whole-cell patch clamp electrophysiology. We found that mutant channels had elevated sensitivity to temperature. More specifically, they displayed faster kinetics at higher temperature. Kinetic shift by change of temperature sensitivity rather than the shift of voltage dependence led to increased availability of I h in conditions promoting FS. Responses to cyclic AMP did not differ between wildtype and mutant channels. Thus, mutant HCN2 channels cause significant cAMP-independent enhanced availability of I h during high temperatures, which may contribute to hyperthermia-induced neuronal hyperexcitability in some individuals with FS.

De novo loss-of-function mutations in CHD2 cause a fever-sensitive myoclonic epileptic encephalopathy sharing features with Dravet syndrome

Dravet syndrome is a severe epilepsy syndrome characterized by infantile onset of therapy-resistant, fever-sensitive seizures followed by cognitive decline. Mutations in SCN1A explain about 75% of cases with Dravet syndrome; 90% of these mutations arise de novo. We studied a cohort of nine Dravet-syndrome-affected individuals without an SCN1A mutation (these included some atypical cases with onset at up to 2 years of age) by using whole-exome sequencing in proband-parent trios. In two individuals, we identified a de novo loss-of-function mutation in CHD2 (encoding chromodomain helicase DNA binding protein 2). A third CHD2 mutation was identified in an epileptic proband of a second (stage 2) cohort. All three individuals with a CHD2 mutation had intellectual disability and fever-sensitive generalized seizures, as well as prominent myoclonic seizures starting in the second year of life or later. To explore the functional relevance of CHD2 haploinsufficiency in an in vivo model system, we knocked down chd2 in zebrafish by using targeted morpholino antisense oligomers. chd2-knockdown larvae exhibited altered locomotor activity, and the epileptic nature of this seizure-like behavior was confirmed by field-potential recordings that revealed epileptiform discharges similar to seizures in affected persons. Both altered locomotor activity and epileptiform discharges were absent in appropriate control larvae. Our study provides evidence that de novo loss-of-function mutations in CHD2 are a cause of epileptic encephalopathy with generalized seizures.

Facial emotion recognition in childhood: the effects of febrile seizures in the developing brain

It has been documented that anteromedial temporal lobe dysfunction can cause impairment in emotional intelligence. In particular, medial temporal lobe epilepsy (MTLE) is associated with disorders in emotion recognition from facial expressions. About one-third of patients with MTLE experienced febrile seizures (FSs) during childhood. In the present study, we investigated facial emotion recognition ability in a group of 38 school-aged children with antecedent FSs and in an age- and sex-matched control group. Children with abnormal general visuoperceptual abilities were excluded. Children with FSs showed lower recognition scores versus controls in both matching (28.64 vs 33.47; p<.0001) and labeling (21.25 vs 23.03; p=.001) facial emotions. Our findings support the hypothesis that FSs can be associated during childhood with a dysfunction within the neural network subserving the processing of facial expressions of the basic emotions.

Children with a history of atypical febrile seizures show abnormal steady state visual evoked potential brain responses

Atypical febrile seizures (FSs) are considered a risk factor for the onset of epilepsy in later life as well as for potential cognitive impairment. However, distinctive characteristics defining the group of children at risk for negative outcomes are not well established. In the following study, children from 6 to 59 months with a history of atypical FSs were investigated using steady state visual evoked potentials (ssVEP), a brain response known to increase with age. Abnormally, low theta and alpha ssVEP brain responses were found in children with a history of atypical FSs.

Collaborative Group for Fever-induced Refractory Epileptic Encephalopathy in School-aged Children. [Fever-induced refractory epileptic encephalopathy in school-aged children: clinical features and outcome-a multicenter study on 13 children]

OBJECTIVE

To analyze the clinical features and outcomes of fever-induced refractory epileptic encephalopathy in school-aged children (FIRES) in China.

METHOD

A retrospective multicenter study on 13 FIRES patients was conducted. By collecting the medical data and follow up research of these patients, the clinical manifestations, clinical courses, investigations, treatments and outcomes of FIRES patients were analyzed.

RESULT

The 13 enrolled patients were previously healthy. The median age at onset was 8.3 years. The male-to-female ratio was 6:7. They exhibited with prolonged refractory status epilepticus after fever onset. All the patients presented with partial seizures, 9 of them had secondary generalized epilepsy; 12 patients had EEG data, 6 of them showed asymmetric diffused slow wave. Seven patients presented with focal or multifocal discharges mostly located in frontotemproal areas. n acute period, many seizures (up to 100) could occur each day. Between seizures, the patients were drowsy or even comatose. Neuroimaging demonstrated normal findings in 10 children. Classical anti-epileptic drugs (AED, 3-7 kinds, median 5) were ineffective; 3 children received anesthesia treatment.Eight patients were admitted to ICU, 6 of them needed mechanical ventilation. One patient died 1 week after discharge. n follow up period, most patients were in a stable and chronic condition. Seizures were controlled by AED only in 1 child. Parents of 1 patient gave up all treatment but the patient still had seizure. Other 10 patients had refractory epilepsy that could not be controlled by 3-4 AEDs. We collected neuroimaging data of 11 patients in follow up period, 1 of the 9 previously normal patients exhibited temporal lobe atrophy, others did not show any change compared with that in acute phase. Only 3 of the 12 surviving patients retained normal cognitive level but all of them could not recover to pre-morbidity status.

CONCLUSION

FIRES is a devastating epileptic encephalopathy with unknown cause. Different kinds of anti-epileptic treatments were given without satisfactory effect, even extensive treatment efforts including intensive care were unsuccessful. Thus the outcome is disastrous in most of the previously healthy children.

The neuroprotective effect of topiramate on the ultrastructure of pyramidal neurons of the hippocampal CA1 and CA3 sectors in an experimental model of febrile seizures in rats

The objective of the current ultrastructural study was to explore the potentiality of the neuroprotective effect of TPM against damage of pyramidal neurons in the hippocampal CA1 and CA3 sectors in an experimental model of febrile seizures (FS) in rats. The FS group exhibited variously pronounced submicroscopic lesions of the neuronal perikarya, including total cell disintegration. Advanced changes induced by hyperthermic stress were manifested by marked degenerative abnormalities, such as substantial swelling of the mitochondria, dilation, degranulation and disintegration of the granular endoplasmic reticulum, and vacuolar changes in the Golgi complex. The most substantially damaged pyramidal neurons showed features of aponecrosis (so-called "dark neurons"), resulting in a marked neuronal loss in the explored areas of the hippocampal cortex. The neurodegenerative changes were accompanied by distinct damage to the blood-brain barrier components. The administration of topiramate at a dose of 80/kg b.m. prior to the induction of hyperthermic stress (as prevention against febrile seizures) caused a substantial neuroprotective action - the drug efficiently lightened the neuronal damage, basically reduced cell aponecrosis and enhanced cell viability. However, TPM applied directly after FS induction did not exert any distinct neuroprotective effect on the perikarya of pyramidal neurons in the hippocampal cortex.

[Expression of brain-derived neurotrophic factor and apoptosis in the brain of rats with repeated febrile seizures]

OBJECTIVE

To study the changes of brain-derived neurotrophic factor (BDNF) following repeated febrile seizures in rats and its possible correlation with neurocyte apoptosis.

METHODS

Fifty-one male Sprague-Dawley (SD) rats were randomly assigned to three groups: normal control (n=14), febrile seizure (FS, n=18), hyperthermia alone (n=19). Febrile seizures were induced by hot water bath. The level of BDNF in the hippocampal homogenate was measured using ELISA and the expression of BDNF in various brain regions was measured by immunohistochemistry. The neurocyte apoptosis of the brain was determined by TdT-mediated biotinylated-dUTP nick end labling (TUNEL).

RESULTS

The level of BDNF in the hippocampus in the FS group(89.9+/-12.5 ng/g)was higher than that in the normal control group(54.4+/-18.9 ng/g)and in the hyperthermia alone group (64.1+/-15.0 ng/g) (P<0.01). The OD value of BDNF positive neurons in various brain regions of the FS group was significantly higher than that of the normal control group (P<0.01) and the hyperthermia alone group (P<0.01). The FS group had significantly higher apoptotic index in various brain regions than the normal control and the hyperthermia alone groups (P<0.01). There was a positive correlation between the expression of BDNF and the apoptotic index in various brain regions (r=0.332, P<0.05).

CONCLUSIONS

BDNF expression in the brain increases following repeated febrile seizures in rats, and the increased BDNF expression is correlated with neurocyte apoptosis.

[Changes in the hippocampal volume in the acute phase following febrile convulsions in children]

OBJECTIVE

To study the changes in the hippocampal volume in the acute phase after febrile convulsions (FC) in children.

METHODS

The brain MRI was performed on 30 children with FC (15 simple and 15 complex) and 30 normal children (control). The hippocampal volume for both sides was compared between groups.

RESULTS

In the control group, the average volume of the right hippocampus was significantly larger than that of the left side (P<0.05). There was no significant difference in the hippocampal volume between the left and right sides in the FC group. The average volumes of both the left and right hippocampus in the FC group (2.03 + or - 0.25 cm(3) and 2.18 + or - 0.21 cm(3) respectively) were enlarged compared to the control group (1.90 + or - 0.24 cm(3) and 1.97 + or - 0.20 cm(3) respectively) (P<0.05). There was no significant difference in the hippocampal volume between the simple and the complex FC groups.

CONCLUSIONS

The hippocampal volume is enlarged in the acute phase after FC in children. The hippocampal volume in children with simple FC is similar to that in children with complex FC in the acute stage.

Ultrastructural features of astrocytes in the cortex of the hippocampal gyrus and in the neocortex of the temporal lobe in an experimental model of febrile seizures and with the use of topiramate

The objective of the current study was ultrastructural assessment of astroglia in specimens of the hippocampal cortex and neocortex of the temporal lobe in our own experimental model of febrile seizures (FS) in rats, as well as the analysis of the influence of a structurally novel broad spectrum anticonvulsant, topiramate (TPM), upon these cells in the CNS regions studied. The current study was inspired by some interesting literature reports on the in vitro investigation into the biological effects of TPM in primary cultures of rat cortical astrocytes and by the lack of data concerning astroglial morphology in vivo in an experimental model with this antiepileptic. In the FS group, the most pronounced changes in the study cell population referred to protoplasmic astroglia and were observed in approximately 3/4 of these cells. The abnormalities were similarly expressed in the two CNS regions studied, in terms of both quantity and quality. They were characterized by considerable swelling and degenerative changes, both in astrocytic perikarya and their processes. Changes were visible in the elements of the granular endoplasmic reticulum and mitochondria, which had a condensed configuration. In the group receiving topiramate directly after the induction of FS, submicroscopic changes in protoplasmic astrocytes were similarly expressed as in the FS group. However, in the group receiving the drug prior to the induction of FS its protective action was observed on the morphology of approximately 1/3 of the population of the protoplasmic astroglial cells. The remaining protoplasmic astrocytes still showed features of considerable or moderately pronounced injury. The beneficial effect of TPM on the ultrastructure of part of the population of the protoplasmic astroglia in the group in which the drug was applied prior to the induction of FS can be explained, among others, by a protective effect of the blood-brain barrier enhanced by the drug administration, as indicated by our earlier findings.

[Protective effect of fructose-1,6-diphosphate against ultrastructural damage in the hippocampus of rats with repeated febrile seizures]

OBJECTIVE

Fructose-1, 6-diphosphate (FDP), serving as a cellular energy substance, has shown its roles in the treatment of hypoxic-ischemic encephalopathy and myocardial damage. The present study aimed at exploring the potentiality of the protective effect of FDP against ultrastructural damage of the hippocampus caused by febrile seizures (FS) in rats.

METHODS

Thirty-six 21-day-old male Sprague-Dawley rats were randomly divided into three groups: untreated FS (control), high-dose FDP-treated FS and low-dose FDP-treated FS. FS were induced by hyperthermal bath. Thirty minutes before FS induction, rats in the high-dose and low-dose FDP-treated groups received a peritoneal injection of FDP at a dosage of 50 and 25 mg per 100 g of body weight respectively, whereas the same volume of 0.9% sodium chloride solution were injected to the rats in the control group. Transmission electron microscopy was used to examine the ultrastructural pathologic changes of neurons and organelles as well as the features of synaptic morphological parameters in the hippocampal CA1 area.

RESULTS

Neuronal degeneration and necrosis, mitochondria swelling, polyribosomes disaggregation from endoplasmic reticula, and golgiosomes dilation in the hippocampal CA1 area in the two FDP intervention groups were less severe compared with the control group. FDP treatment resulted in significant increases in postsynaptic density thickness (F=12.47, P<0.01), synaptic active zone length (F=14.75, P<0.01) and synaptic interface curvature (F=3.77, P<0.05), as well as a shorter interspace of neural synapses (F=7.29, P<0.01) when compared with the control group. There were no significant differences in the ultrastructural changes between the two FDP treatment groups.

CONCLUSIONS

FDP can ameliorate ultrastructural damage in the hippocampus caused by FS in rats. However, further research is warranted for a reasonable and effective dosage of FDP.

Long-term neuroplasticity effects of febrile seizures in the developing brain

Febrile seizures (FS) are the most common seizure disorder in childhood, occurring in 2%-5% of children. Regarding the large number of children with FS, it is important to delineate whether early-life FS alters long-term neuroplasticity, especially the neurocognitive function and subsequent temporal lobe epilepsy (TLE). Recent epidemiological studies reassure that most FS do not adversely affect global intelligence and hippocampal function, such as memory. However, there are concerns regarding those children who experience FS during the first postnatal year, having prior developmental delay and pre- or peri-natal events. The epidemiological data do not support a causal relationship between FS and TLE. However, magnetic resonance imaging studies confirmed that prolonged and focal FS can occasionally produce acute hippocampal injury that evolves into atrophy. Moreover, the common coexistence of hippocampal sclerosis and asymmetric cortical dysgenesis in TLE patients argues for a 'double-hit' theory for TLE. Animal studies have revealed that the exposure of hippocampal neurons to FS early in life, particularly prolonged or frequently repetitive FS, or together with brain malformation, may lead to sustained dysfunction of these cells including long-term memory impairment or epileptogenesis, in spite of the absence of neuronal damage. Recent clinical and molecular genetic studies suggest that the relationship between FS and later epilepsy is frequently genetic, and there are a number of syndrome-specific genes for FS. However, these channelopathies account for a small proportion of FS cases. The clinical management, therefore, is based mainly on the phenotypic features of FS and the subsequent seizures.

Ultrastructure of the blood-brain barrier of the gyrus hippocampal cortex in an experimental model of febrile seizures and with the use of a new generation antiepileptic drug--topiramate

The ultrastructure of the blood-brain barrier (BBB) of the gyrus hippocampal cortex in an experimental model of febrile seizures in rats and the effect of a new generation antiepileptic drug, topiramate, on the morphological status of this barrier were investigated. Advanced changes indicating a substantial increase in BBB permeability were observed in the animals with induced febrile seizures (FS), with approximately 2/3 of capillaries and perivascular astroglial processes being affected. Almost total occlusion of the capillary lumen was frequently seen, caused by damaged endothelial lining and by external pressure from markedly swollen perivascular astrocytic processes. Mitochondrial changes predominated among the abnormalities found in endoplasmic organelles of endothelial cells. Lesions in the BBB coexisted with damage to pyramidal neurons, mainly with features of aponecrosis ("dark neurons"). The study on topiramate seems to demonstrate its protective action on the BBB components of the ammonal cortex in the group receiving the drug as prevention, i.e. against febrile seizures. It was found to prevent marked BBB damage in over half of the capillaries. However, the application of topiramate directly after FS induction had no distinct beneficial effect on the structural BBB components.

Decompressive hemicraniectomy in a space-occupying presentation of hemiconvulsion–hemiplegia–epilepsy syndrome

A case of an acute life-threatening presentation of hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome requiring an urgent decompressive hemicraniectomy is described. A 9 month-old baby had a status epilepticus following a sustained fever, leading to a comatose state and a right pupillary dilatation associated with a left hemiplegia. The MRI showed a swelling right hemisphere with marked temporal herniation. The baby underwent a decompressive right hemicraniectomy with temporal cortical biopsies. The post-operative course was favourable. The histological findings were unspecific, showing a gliotic spongiosis with disseminated granular cells. The post-operative MRI depicted a right hemisphere atrophy. To our knowledge, a space-occupying presentation of HHE syndrome requiring surgical decompression has never been described before while only a few reports dealt with the neuropathological aspects of this syndrome.

Fever, febrile seizures and epilepsy

Seizures induced by fever (febrile seizures) are the most common type of pathological brain activity in infants and children. These febrile seizures and their potential contribution to the mechanisms of limbic (temporal lobe) epilepsy have been a topic of major clinical and scientific interest. Key questions include the mechanisms by which fever generates seizures, the effects of long febrile seizures on neuronal function and the potential contribution of these seizures to epilepsy. This review builds on recent advances derived from animal models and summarizes our current knowledge of the mechanisms underlying febrile seizures and of changes in neuronal gene expression and function that facilitate the enduring effects of prolonged febrile seizures on neuronal and network excitability. The review also discusses the relevance of these findings to the general mechanisms of epileptogenesis during development and points out gaps in our knowledge, including the relationship of animal models to human febrile seizures and epilepsy.

Molecular neuropathology of temporal lobe epilepsy: complementary approaches in animal models and human disease tissue

Patients with temporal lobe epilepsies (TLE) frequently develop pharmacoresistance to antiepileptic treatment. In individuals with drug-refractory TLE, neurosurgical removal of the epileptogenic focus provides a therapy option with high potential for seizure control. Biopsy specimens from TLE patients constitute unique tissue resources to gain insights in neuropathological and molecular alterations involved in human TLE. Compared to human tissue specimens in most neurological diseases, where only autopsy material is available, the bioptic tissue samples from pharmacoresistant TLE patients open rather exceptional preconditions for molecular biological, electrophysiological as well as biochemical experimental approaches in human brain tissue, which cannot be carried out in postmortem material. Pathological changes in human TLE tissue are multiple and relate to structural and cellular reorganization of the hippocampal formation, selective neurodegeneration, and acquired changes of expression and distribution of neurotransmitter receptors and ion channels, underlying modified neuronal excitability. Nevertheless, human TLE tissue specimens have some limitations. For obvious reasons, human TLE tissue samples are only available from advanced, drug-resistant stages of the disease. However, in many patients, a transient episode of status epilepticus (SE) or febrile seizures in childhood can induce multiple structural and functional alterations that after a latency period result in a chronic epileptic condition. This latency period, also referred to as epileptogenesis, cannot be studied in human TLE specimens. TLE animal models may be particularly helpful in order to shed characterize new molecular pathomechanisms related to epileptogenesis and open novel therapeutic strategies for TLE. Here, we will discuss experimental approaches to unravel molecular-neuropathological aspects of TLE and highlight characteristics and potential of molecular studies in human and/or experimental TLE.

Electroclinical features of a family with simple febrile seizures and temporal lobe epilepsy associated with SCN1A loss-of-function mutation

PURPOSE

To report in detail the electroclinical features of a large family in which we recently identified a missense mutation (M145T) of a well-conserved amino acid in the first transmembrane segment of domain I of the human SCN1A. We showed that the mutation is associated with a loss of SCN1A function.

METHODS

The family originates from southern Italy and contains 35 members spread over four generations. Of the 14 affected individuals, the 13 still living members (7 males, mean age 36.6 +/- 20.4) underwent a complete electroclinical evaluation.

RESULTS

All 13 affected family members had febrile seizures (FS) up to the age of 6 years. Age at onset of FS ranged from 5 to 45 months with a mean age of 12.8 +/- 12.9 months. One of the 13 was affected by post-traumatic epilepsy. Three of the 13 later developed temporal lobe epilepsy (TLE) with both simple focal seizures, and also very rare focal complex or nocturnal secondary generalized tonic-clonic seizures. In two of the three patients who later developed TLE, the MRI studies revealed mesial temporal sclerosis.

CONCLUSIONS

Our findings illustrate that SCN1A mutations can cause simple FS associated with TLE, which differ from the characteristic clinical spectrum of GEFS+. It is open to conjecture if this unusual phenotype might at least in part be related to the fact that M145T is the first missense mutation found in DIS1 of SCN1A.

An unspecified clinical syndrome in mentally retarded patients with bilateral mesial temporal sclerosis

PURPOSE

The association of febrile convulsions and mesial temporal sclerosis (MTS) is a well-known phenomenon. However, the effects of mental retardation on febrile convulsions and MTS have not been investigated previously. The aim of this study is to investigate the relation of mental retardation to febrile convulsions especially as febrile status epilepticus and MTS.

METHODS

We describe three patients who have bilateral mesial temporal sclerosis with mental retardation and a history of febrile status epilepticus (FSE), and have clinically typical mesial temporal lobe epilepsy (MTLE).

RESULTS

The FRSB and neuropsychology test revealed executive dysfunction in patients whose bilateral MTS had a benign course, which was unexpected.

CONCLUSIONS

Febrile status epilepticus might have a role in the development of their mental retardation. This study also pointed out that MTS might have subtypes as a result of our attempts at distinguishing patients with MTS.

Hippocampal volumes and diffusion-weighted image findings in children with prolonged febrile seizures

OBJECTIVES

To assess hippocampal volumes (HV) and signal changes on diffusion-weighted imaging (DWI) within 5 days of prolonged febrile seizures (PFS) and compare them with the PFS duration and EEG.

METHODS

We studied 12 children (mean age: 32 +/- 21 months, range 10 months-5 years) within 5 days of a first episode of PFS (a seizure or series of seizures lasting for 30 min or longer, without return of consciousness between the seizures). The HV measurements were carried out using high-resolution magnetic resonance imaging and signal intensity abnormalities were evaluated visually on DWI. HV in patients were compared with those of 13 neurologically normal controls (mean age 31 +/- 16 months, range 15 months-5 years). HV abnormalities correlated with PFS duration. HV and DWI abnormalities were compared with EEG abnormalities.

RESULTS

Seizure duration ranged from 40 to 95 min. In seven out of twelve patients, seizures were refractory and lasted for 60 min or longer despite intravenous infusion of diazepam. In the patients with PFS for 60 min or longer, HV were significantly larger than that of controls. In all patients, there was a positive correlation between HV and seizure duration. DWI showed hyperintensity in unilateral hippocampus in three patients with intractable seizures, ipsilateral thalamus in two, and cingulate in one. EEG showed abnormalities in temporal areas ipsilateral to the DWI abnormalities in these patients.

CONCLUSIONS

Large HV and hippocampal hyperintensity on DWI were seen in patients with refractory PFS. Our results suggest that medically refractory PFS lasting for 60 min or longer may cause structural changes in limbic structures that could promote later epileptogenesis.

Neuropathological and MRI findings in an acute presentation of hemiconvulsion-hemiplegia: a report with pathophysiological implications

The mechanisms underlying the hemiconvulsion-hemiplegia-epilepsy syndrome (HHE) remain unclear. The current proposed pathogenic mechanism is a neuronal injury induced by venous thrombosis and/or hypoxia. Previous abnormalities of the brain were suggested as underlying mechanism.

MATERIALS AND METHODS

We report a patient who presented acutely with hemiconvulsion-hemiplegia (HH) syndrome, but unfortunately died. We discuss the possible pathophysiology of the HH syndrome and possible therapeutic implications utilizing the data from neuroimaging and pathological studies. Post-mortem examination was performed including immunohistochemistry and electron microscopy of the brain tissue.

RESULTS

The abnormalities in diffusion-weighted imaging indicate cytotoxic edema of the epileptic hemisphere. The pathological studies confirmed a right homogenous hemispheric edema without evidence of any malformation, inflammatory, infectious or metabolic disease. We found axonal damages in the right thalamus confirmed by anti-neurofilament staining.

DISCUSSION

The pathological studies suggest that cytotoxic edema is responsible for neuronal damage. In HH syndrome, two mechanisms playing a role in the development of a later epilepsy could suggest delayed cell death induced by cytotoxic edema and/or thalamic dysfunction causing a disruption of thalamo-cortical circuit. In acute presentation, the use of anti-edema therapy should be discussed to prevent the cell injury.

Topiramate as a neuroprotectant in the experimental model of febrile seizures

PURPOSE

The aim of the study wad to estimate a potentially neuroprotective effect of topiramate (TPM) in the experimental model of FS.

MATERIAL AND METHODS

24 young male rats divided in 4 groups were involved in the study. Febrile seizures were induced by placing the animals in 45 degrees C warm water bath for four consecutive days. TPM at the dose 80 mg/kg b.m. was administered: before the FS and immediately after the FS. FS group and control rats received only normal saline. Thereafter hippocampal slices were prepared to performing histological and morphometric examination.

RESULTS

Morphometric investigations revealed that FS caused death of 60% of the neurons in sector CA1 and a half of them in sector CA3. Histological examinations of hippocampal slices showed that TPM at a dose of 80 mg/kg b.m., administered before the seizures, considerably improved CA1 and CA3 pyramidal cell survival. Similar neuroprotective effect, but in a markedly lesser degree was observed when TPM was administrated after the FS.

CONCLUSIONS

Our findings seem to confirm that FS exert a strong destructive effect on the sensitive hippocampal neurons and on the neuroprotective properties of TPM in this process, which may have practical implications. It can be assumed that in children with recurrent and prolonged FS, prophylactic drug administration could prevent hippocampal sclerosis and development of symptomatic epilepsy.

Hippocampal volumes and diffusion-weighted image findings in children with prolonged febrile seizures

OBJECTIVES

To assess hippocampal volumes (HV) and signal changes on diffusion-weighted imaging (DWI) within 5 days of prolonged febrile seizures (PFS) and compare them with the PFS duration and EEG.

METHODS

We studied 12 children (mean age: 32 +/- 21 months, range 10 months-5 years) within 5 days of a first episode of PFS (a seizure or series of seizures lasting for 30 min or longer, without return of consciousness between the seizures). The HV measurements were carried out using high-resolution magnetic resonance imaging and signal intensity abnormalities were evaluated visually on DWI. HV in patients were compared with those of 13 neurologically normal controls (mean age 31 +/- 16 months, range 15 months-5 years). HV abnormalities correlated with PFS duration. HV and DWI abnormalities were compared with EEG abnormalities.

RESULTS

Seizure duration ranged from 40 to 95 min. In seven out of twelve patients, seizures were refractory and lasted for 60 min or longer despite intravenous infusion of diazepam. In the patients with PFS for 60 min or longer, HV were significantly larger than that of controls. In all patients, there was a positive correlation between HV and seizure duration. DWI showed hyperintensity in unilateral hippocampus in three patients with intractable seizures, ipsilateral thalamus in two, and cingulate in one. EEG showed abnormalities in temporal areas ipsilateral to the DWI abnormalities in these patients.

CONCLUSIONS

Large HV and hippocampal hyperintensity on DWI were seen in patients with refractory PFS. Our results suggest that medically refractory PFS lasting for 60 min or longer may cause structural changes in limbic structures that could promote later epileptogenesis.

Inflammation contributes to seizure-induced hippocampal injury in the neonatal rat brain

OBJECTIVE

The extent of neuronal injury in the hippocampus produced by experimental status epilepticus (SE) is age dependent and is not readily demonstrable in many models of neonatal seizures. Neonatal seizures often occur in clinical settings that include an inflammatory component. We examined the potential contributory role of pre-existing inflammation as an important variable in mediating neuronal injury.

MATERIALS AND METHODS

Postnatal day 7 (P7) and P14 rat pups were injected with lipopolysaccharide (LPS), 2 h prior to SE induced by lithium-pilocarpine (LiPC). Neuronal injury was assessed by well-described histologic methods.

RESULTS

While LPS by itself did not produce any discernible cell injury at either age, this treatment exacerbated hippocampal damage induced by LiPC-SE. The effect was highly selective for the CA1 subfield.

CONCLUSIONS

Inflammation can contribute substantially to the vulnerability of immature hippocampus to seizure-induced neuronal injury. The combined effects of inflammation and prolonged seizures in early life may impact long-term outcomes of neonatal seizures.

Prolonged febrile seizures are associated with hippocampal vasogenic edema and developmental changes

PURPOSE

There is mounting evidence that a prolonged febrile seizure (PFS) can cause acute hippocampal edema although the nature of that edema remains uncertain. The principal aims of the current study were: (1) to use apparent diffusion coefficient (ADC) measurements to further characterize the hippocampal edema previously identified within 5 days of a PFS, and (2) to determine whether the age dependency of ADC in the hippocampus is different in patients when compared to a control population following a PFS.

METHODS

Diffusion weighted imaging was acquired in 23 children within 5 days of a PFS, and in 14 of these children a mean of 5.5 months later. Twenty-four control children were enrolled.

RESULTS

There was a reduction in ADC between the acute and follow-up investigations [mean reduction = 0.0072 mm2/s/month since PFS (95% confidence interval; 0.0001-0.014 mm2/s/month since PFS), p = 0.048] consistent with early vasogenic edema, followed by recovery in children investigated within 2 days of a PFS. In addition, the behavior of ADC with respect to age was different in patients when compared to control subjects [mean difference in slope =-0.155 mm2/s/log10 age (95% confidence interval; -0.290-0.0203 mm2/s/log10 age), p = 0.029], in that the expected age dependence was observed only in the control subjects.

CONCLUSION

We suggest that these latter findings are most consistent with a preexisting developmental hippocampal abnormality that may predispose individuals to having a PFS.

Increased IL-1beta production from dsRNA-stimulated leukocytes in febrile seizures

This study examined the possibility that children with and without a history of febrile seizures might mount different immune responses to double-stranded ribonucleic acid, which is a common viral factor that induces host cell immune responses, and is recognized by Toll-like receptor 3. The production of interleukin-1beta and interferon-alpha from double-stranded ribonucleic acid-stimulated leukocytes was examined in 27 children (age 3.6+/-0.3 years) with a history of febrile seizures and in 18 children (age 3.4+/-0.2 years) without a history of febrile seizures. Significantly (P=0.0007) increased interleukin-1beta production was observed in children with a history of febrile seizures, compared with control subjects. When patients with a single prior episode of febrile seizures (n=9) and those with multiple prior episodes of febrile seizures (n=18) were compared, a significant difference in interleukin-1beta production was not observed. Genotyping of interleukin-1beta(-511), Toll-like receptor 3, Toll-IL-1 receptor domain-containing adapter inducing interferon-beta, and interleukin-1 receptor antagonist polymorphisms revealed no significant differences in allelic distribution among febrile seizure patients and control subjects. Interleukin-1beta production was not significantly influenced by genotype. Viral infection results in increased interleukin-1beta production in febrile seizure patients, and this may play a role in febrile seizures.

Diffusion MRI abnormalities after prolonged febrile seizures with encephalopathy

BACKGROUND

Patients with encephalopathy heralded by a prolonged seizure as the initial symptom often have abnormal subcortical white matter on diffusion-weighted MRI (DWI).

OBJECTIVE

To determine if these patients share other common features.

METHODS

Patients with encephalopathy heralded by a prolonged seizure and followed by the identification of abnormal subcortical white matter on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed.

RESULTS

Seventeen patients were identified, ages 10 months to 4 years. All had a prolonged febrile seizure (longer than 1 hour in 12 patients) as their initial symptom. Subsequent seizures, most often in clusters of complex partial seizures, were seen 4 to 6 days after the initial seizure in 16 patients. Outcome ranged from almost normal to severe mental retardation. MRI performed within 2 days of presentation showed no abnormality. Subcortical white matter lesions were observed on DWI between 3 and 9 days in all 17 patients. T2-weighted images showed linear high intensity of subcortical U fibers in 13 patients. The lesions were predominantly frontal or frontoparietal in location with sparing of the perirolandic region. The diffusion abnormality disappeared between days 9 and 25, and cerebral atrophy was detected later than 2 weeks. Three patients having only frontal lesions had relatively good clinical outcome.

CONCLUSIONS

Although the pathophysiologic mechanism remains unknown, these patients seem to have a distinctive encephalopathy syndrome. MRI is helpful in establishing the diagnosis of this encephalopathy.

[Effect of carbon monoxide and nitric oxide on the apoptosis of hippocampal neurons in rats with febrile seizures]

OBJECTIVE

Febrile seizure (FS) is the most common type of seizure disorders in children. Recurrent FS can cause hippocampal neurons injury. At the same time heme oxygenase/carbon monoxide (HO/CO) system and nitric oxide synthase/nitric oxide (NOS/NO) system were up-regulated and interacted each other. This study examined the effects of the two systems on the apoptosis of hippocampal neurons in rats with recurrent FS.

METHODS

FS was induced in rats by exposure to warm water bath (45.2 degrees C), once every 2 days, 10 times in all. Sprague-Dawley (SD) rats aged 21 days were randomly assigned into four groups: Control (37 degrees C water bath exposure), FS, FS + ZnPP-IX (HO inhibitor) and FS + L-NAME (NOS inhibitor) groups. The apoptosis of hippocampal CA1 neurons was detected by TUNEL.

RESULTS

After recurrent FS, the apoptotic cells in the hippocampal CA1 neurons increased by 225% compared with those in the Control group (P < 0.01). The apoptotic cells in the FS+ZnPP-IX group increased by 62% and 425% compared with those in the FS and the Control groups (both P < 0.01). The apoptotic cells in the FS + L-NAME group decreased by 38% compared with those in the FS group (P < 0.01) and increased by 100% compared with those in the Control group (P < 0.05).

CONCLUSIONS

In recurrent FS, exogenous administration of HO inhibitor ZnPP-IX may induce an increase of apoptotic cells in hippocampal neurons, while NOS inhibitor L-NAME may decrease the apoptotic cells. The results suggest that the HO/CO system might alleviate neuronal damage, while NOS/NO system might augment neuronal damage.

Clinical characteristics in focal cortical dysplasia: a retrospective evaluation in a series of 120 patients

Focal cortical dysplasias (FCDs) are increasingly diagnosed as a cause of symptomatic focal epilepsy in paediatric and adult patients. However, little is known about the clinical characteristics of epilepsy in these patients. In order to elucidate the clinical characteristics of their epilepsy, 120 pharmacoresistant patients including children and adults with histologically proven FCD were studied retrospectively. Age at seizure onset was analysed in the total group and compared between subgroups with different localization and different histological subtypes of FCD. The role of febrile seizures with respect to dual pathology was investigated. Seizure semiology was analysed focusing on initial seizure type and change of seizure semiology during the course of disease. Finally, transient responsiveness to antiepileptic drug therapy was studied. In the majority of patients, epilepsy began in the first 5 years of life. However, onset of epilepsy could also occur in the second or third decade until the age of 60. Age at epilepsy onset was not significantly different between temporal, extratemporal and multilobar localization of FCD. Patients without cytoarchitectural abnormalities (mild malformations of cortical development, FCD 1a according to Palmini) had significantly later epilepsy onset (P= 0.001) compared with patients with cytoarchitectural abnormalities (FCD 1b, 2a and 2b according to Palmini). In patients with additional hippocampal sclerosis (dual pathology) febrile seizures were significantly more frequently reported (P = 0.02) than in patients without dual pathology. Moreover, patients with dual pathology and febrile seizures significantly more frequently presented with severe hippocampal sclerosis (Wyler Grade 3-4) as compared with patients with dual pathology in the absence of febrile seizures (P = 0.03). First observed seizures were mainly tonic or generalized tonic-clonic. A change of seizure semiology seemed to be age-dependent and occurred between the age of >1 and 14 years. About 15.8% of the patients presented with status epilepticus during the course of disease. About 17% of the patients showed transient responsiveness (> or =1 year seizure freedom) to antiepileptic drug therapy either after initial therapy (50%) or later in the course of epilepsy (50%). Patients with FCD represent a heterogeneous group. Different age at epilepsy onset and transient responsiveness to antiepileptic drugs in approximately 17% of patients may reflect different dynamics in epileptogenicity of the underlying FCD. Dual pathology may be associated with different pathomechanisms in patients with and without febrile seizures.

Diffusion tensor imaging in medial temporal lobe epilepsy with hippocampal sclerosis

Interictal diffusion imaging studies in patients with medial temporal lobe epilepsy (MTLE) accompanied by hippocampal sclerosis (HS) have shown an increased diffusivity in the epileptogenic hippocampus. In this study, we wanted to explore the whole brain in order to determine if MTLE could have an impact on the organization and the architecture of a large cerebral network and to identify clinical factors that could mediate diffusion abnormalities. Diffusion tensor imaging (DTI) and statistical parametric mapping of the entire brain were performed in 35 well-defined MTLE patients and in 36 healthy volunteers. SPM analyses identified three abnormal areas: an increased diffusivity was detected in the epileptic hippocampus and the ipsilateral temporal structures associated with a decreased anisotropy along the temporal lobe, a decreased diffusivity was found in the contralateral non-sclerotic hippocampus, the amygdala, and the temporal pole, and finally, a decreased anisotropy was noted ipsilaterally in posterior extratemporal regions. Duration of epilepsy, age at onset, and the frequency of generalized tonic-clonic seizures or partial complex seizures did not correlate with the presence of diffusion abnormalities. Region of interest analysis in the hippocampus/parahippocampus demonstrated a correlation between lower ipsilateral diffusivity values and occurrence of epigastric aura and between higher anisotropy values in both hemispheres and history of febrile seizures. In conclusion, this study showed that diffusion abnormalities are not restricted to the pathologic hippocampus and involve a larger network. This pattern may indirectly reflect the epileptogenic network and may be interpreted as a cause or a consequence of epilepsy.

Gender differences in febrile seizure-induced proliferation and survival in the rat dentate gyrus

PURPOSE

Febrile seizures are fever-associated early-life seizures that are thought play a role in the development of epilepsy. Seizure-induced proliferation of dentate granule cells has been demonstrated in several adult animal models and is thought to be an integral part of epileptogenesis. The aim of the present study was to investigate proliferation and survival of dentate gyrus (DG) cells born after early-life hyperthermia (HT)-induced seizures in male and female rats.

METHODS

At postnatal day (PN) 10, male and female rats were exposed to heated air to induce seizures. Littermates were used as normothermia controls. Convulsive behavior was observed by two researchers. From PN11 to PN16, rats were injected with bromodeoxyuridine (BrdU) to label dividing cells. The number of BrdU-immunoreactive cells in the DG was counted at PN17 and PN66.

RESULTS

At PN17, male as well as female HT rats had the same amount of BrdU-positive cells compared with controls. At PN66, significantly more BrdU-positive cells were left in HT females (53%) than in controls (44%, percentage of BrdU-positive cells at PN17), whereas no difference was found between HT males and male controls. The net result of proliferation and survival at PN66 was that female HT rats had the same number of BrdU-immunoreactive cells as controls, whereas male HT rats had 25% more BrdU-immunoreactive cells than did controls (p < 0.05).

CONCLUSIONS

Early-life seizures cause a sexually dimorphic cytogenic response that results in an increased population of newborn DG cells in young adult males, while leaving that of young adult females unaltered.

Losing neurons: selective vulnerability and mesial temporal sclerosis

Mesial temporal sclerosis (MTS) is found in about two-thirds of patients with refractory temporal lobe epilepsy (TLE), and surgical removal of the sclerotic structures eliminates seizures in the majority of cases undergoing surgical resection. Although multiple factors have been implicated in the genesis of MTS, it is still unclear why some individuals are more likely to develop hippocampal sclerosis than others. Epileptologists have proposed that there must be at least two factors involved-an initial precipitating injury (IPI), such as a prolonged febrile seizure, CNS infection, or head trauma, and a second factor that increases vulnerability to neuronal injury. This has been termed the "two-hit hypothesis." Three of the many factors that could possibly heighten susceptibility to neuronal injury and MTS are discussed here. These are microdysgenesis, hippocampal dysgenesis, prior seizures, and genetic predisposition. We conclude that there is currently no compelling evidence to support a role for microdysgenesis in MTS. Hippocampal dysgenesis, on the other hand, may account for febrile seizures and possibly MTS in a small subpopulation of patients with TLE. Additional larger studies are needed to confirm these findings. Experimental evidence indicates that an epileptogenic hippocampus can result from prolonged febrile seizures in infant rats, even though these seizures do not cause MTS in the rat. It is not known if this pathophysiological sequence occurs in humans. Lastly, there appears to be a strong genetic component that predisposes some individuals to MTS, regardless of whether they experience an IPI.

[Hemiconvulsion-hemiplegia syndrome: two case reports with findings from magnetic resonance imaging of the brain in diffusion-weighted sequences]

INTRODUCTION

Hemiconvulsion-hemiplegia (HH) syndrome is characterised by prolonged hemiclonic seizures followed by, very often permanent, hemiplegia. We report the cases of two patients with HH syndrome; in addition, the paper also includes a discussion of the value of neuroimaging in its diagnosis, including the use of magnetic resonance imaging (MRI) of the brain in diffusion-weighted sequences, and its clinical-radiological progression.

CASE REPORTS

Case 1: a 16-month-old female who was admitted to hospital owing to right-side hemiclonic seizures, with a febrile condition, that lasted at least 30 minutes, and persistent hemiparesis on the right-hand side of the body. Results of an initial computerised tomography (CT) brain scan were normal. Brain MRI at 3 days: T2 weighted sequences were normal; diffusion-weighted sequences showed lowered diffusion in the temporoparietooccipital region in the left hemisphere. Brain CT scan at 6 months: hemiatrophy on the left-hand side of the brain. Paresis of the right hand continues at the age of 4 years and 8 months; no further seizures have occurred and the patient's psychic development is normal. Case 2: a female aged 2 years and 6 months who was admitted to the Paediatric Intensive Care Unit owing to right-side hemiclonic seizures, with a feverish condition, lasting between 35-40 minutes, with persistent hemiplegia on the right-hand side of the body. The patient had a history of psychomotor retardation secondary to chromosome pathology; findings from a brain CT scan were normal. CT scan at 48 hours after the episode: edema in the left hemisphere of the brain. Brain MRI at 7 days following hospital admission: extensive involvement of the left hemisphere of the brain could be seen in T2 weighted sequences and in diffusion-weighted sequences. CT scan at 3 months: hemiatrophy on the left-hand side of the brain. Hemiparesis persists at the age of 5 years and 4 months; the patient has had no further seizures and attends specialised schooling.

CONCLUSION

Although rare in our environment, HH syndrome can be seen in the context of hemiclonic febrile conditions. MRI of the brain in diffusion-weighted sequences may be the only means of proving the initial brain lesion.

Expression of Hsp72 in lymphocytes in patients with febrile convulsion

The pathophysiology of febrile convulsion, the most common childhood neurologic disease, remains unclear. In this study, we investigated what role a heat shock protein plays in this disease. We enrolled eight boys and two girls with febrile convulsion and 10 age-matched healthy controls. We did a biosynthetic evaluation of both groups by separating lymphocytes and measuring the expression of heat shock protein 72 before and after heat shock treatment. Before the treatment, both groups were found to have small amounts of constitutive heat shock protein 72. Afterwards, its expression increased in both groups, and no statistical difference was found between the increases in the two groups. In addition, there was no obvious difference in the susceptibility to produce heat shock proteins. However, the febrile convulsion group was found to have a significant decrease in phosphorylation of heat shock protein 72. These results suggest the possible involvement of post-translational modification of heat shock proteins, most likely phosphorylation, in the pathogenesis of febrile convulsion.

[Effect of endogenous heme oxygenase-carbon monoxide on brain damage induced by recurrent febrile seizures]

OBJECTIVE

Febrile seizures (FS) are the most common seizure disorders in children. Approximately one third of children with a febrile seizure have recurrent events. Although most FS may not represent a serious health problem, those that are more prolonged and recurrent may cause hippocampal damage which is the most important pathological basis of temporal lobe epilepsy. The present study aimed to explore the effect of endogenous heme oxygenase (HO)-carbon monoxide (CO) system on brain damage induced by recurrent FS.

METHOD

Twenty-four Sprague-Dawley rats aged 21 days were randomly divided into three groups: Control group (immersed in 37.0 degrees C water, n = 8), FS group (immersed in 45.2 degrees C water, n = 8), FS + zinc protoporphyrin (ZnPPIX) group (immersed in 45.2 degrees C water, n = 8). FS in rats were induced ten times in a bath of warm water, once every 2 days. The indirect production of CO in plasma was detected by a dual wavelengh spectrophotometer. The intensity, latency, duration and rectal temperature of the seizure in rats were recorded. Morphologic changes of hippocampal neurons were observed with HE staining. The ultrastructural changes of the hippocampal neurons were observed under electron microscope. Semiquantitative analysis of hippocampal neurons was carried out by using Nissl stain.

RESULT

After recurrent FS, the content of CO in plasma in FS group was increased as compared with that in control group (P < 0.01). The content of CO in plasma in FS + ZnPPIX group was decreased as compared with that in FS group (P < 0.01), while no significant difference in CO content was found as compared with that in control group (P > 0.05). In FS group, with the increase of seizure number, there was a trend of gradual prolongation of the seizure duration. In FS + ZnPPIX group, the seizure latency was gradually shortened and the seizure duration was further prolonged. There were no significant differences in seizure intensity and rectal temperature between the two groups. After recurrent FS, by using light microscope we could see that the arrangement of hippocampal neurons was disordered, polarity was not clear and vacuolization appeared in some neurons. At the same time the ultrastructure of hippocampal neurons under electron microscope changed, which manifested as mitochondrial swelling, dissolved and ruptured ridge and vacuole formation, and dilated rough endoplasmic reticulum (RER). ZnPPIX aggravated neuronal injury. No obvious loss of hippocampal neurons was observed in FS group, while the number of hippocampal neurons in CA(1) and CA(3) subfields in FS + ZnPPIX group decreased respectively as compared with that in FS group and in control group (P < 0.01 for all).

CONCLUSION

The study by using ZnPPIX which is an inhibitor of HO showed that endogenous HO/CO might act as a protective factor in FS-induced brain damage.