Mossy fiber plasticity and enhanced hippocampal excitability, without hippocampal cell loss or altered neurogenesis, in an animal model of prolonged febrile seizures. (49/310)

Seizures induced by fever (febrile seizures) are the most frequent seizures affecting infants and children; however, their impact on the developing hippocampal formation is not completely understood. Such understanding is highly important because of the potential relationship of prolonged febrile seizures to temporal lobe epilepsy. Using an immature rat model, we have previously demonstrated that prolonged experimental febrile seizures render the hippocampus hyperexcitable throughout life. Here we examined whether (1) neuronal loss, (2) altered neurogenesis, or (3) mossy fiber sprouting, all implicated in epileptogenesis in both animal models and humans, were involved in the generation of a pro-epileptic, hyperexcitable hippocampus by these seizures. The results demonstrated that prolonged experimental febrile seizures did not result in appreciable loss of any vulnerable hippocampal cell population, though causing strikingly enhanced sensitivity to hippocampal excitants later in life. In addition, experimental febrile seizures on postnatal day 10 did not enhance proliferation of granule cells, whereas seizures generated by kainic acid during the same developmental age increased neurogenesis in the immature hippocampus. However, prolonged febrile seizures resulted in long-term axonal reorganization in the immature hippocampal formation: Mossy fiber densities in granule cell- and molecular layers were significantly increased by 3 months (but not 10 days) after the seizures. Thus, the data indicate that prolonged febrile seizures influence connectivity of the immature hippocampus long-term, and this process requires neither significant neuronal loss nor altered neurogenesis. In addition, the temporal course of the augmented mossy fiber invasion of the granule cell and molecular layers suggests that it is a consequence, rather than the cause, of the hyperexcitable hippocampal network resulting from these seizures.  (+info)

A retrospective analysis of patients with febrile seizures followed by epilepsy. (50/310)

This study was performed to investigate some clinical parameters of febrile seizures (FSs) in patients with epilepsy, testing any possible correlation between those parameters and the type of subsequent epilepsy. One hundred and nine patients with epilepsy having a history of FSs were evaluated for age at onset of FSs, interval between first FS and first afebrile seizure, recurrence rate, type of FSs, incidence of febrile status, family history for epilepsy and for FSs and the neurological status of the patient. The epilepsy that developed subsequently, were classified as generalised versus partial and also according to their syndromic subgroups. In temporal lobe epilepsy with mesial temporal sclerosis (TLE-MTS), statistical analyses revealed a younger age at onset of FSs, and a high incidence of episodes of febrile status and of complex FSs. Clinical characteristics of FSs followed by partial epilepsies were younger age at onset, presence of focal features and of febrile status, longer interval between the first FS and the first afebrile seizure, and a high incidence of FSs in the family history. In generalised epilepsies, however, a shorter interval between the first FS and the first afebrile seizure, a high incidence of single FS and of a family history of epilepsy were predominating characteristics. Results suggest that certain features of FSs may be predictive of a particular type of subsequent epilepsy.  (+info)

From swelling to sclerosis: acute change in mesial hippocampus after prolonged febrile seizure. (51/310)

Mesial temporal sclerosis (MTS) has been linked to prolonged febrile seizures. The sequence of changes in the temporal lobe/hippocampus following prolonged febrile seizures and status epilepticus is beginning to be elucidated. We obtained repeated magnetic resonance imaging (MRI) volumetric analysis of the hippocampi in a 23-month-old boy after a prolonged focal febrile seizure. Three days after a prolonged left focal febrile seizure, brain MRI showed increased T2 weighted signal and increased volume (swelling) of the right hippocampus. Repeat MRI 2 months later demonstrated sclerosis of the right hippocampus. Review of the literature shows four other children with prolonged focal seizures associated with the MRI sequence of temporal lobe swelling followed by sclerosis. All had left focal seizures followed by right MTS. Our patient demonstrates a shorter interval for the radiologic development of hippocampal sclerosis compared to other reports.  (+info)

Pre-eclampsia and febrile convulsions. (52/310)

An association between pre-eclampsia and febrile convulsions has been reported, but the association may not be causal. We compared the risk of febrile convulsions in 14 974 children who had been exposed to pre-eclampsia in fetal life with that of 39 210 unexposed children. Children exposed to pre-eclampsia had a slightly increased risk of febrile convulsions, but the association was apparently caused by a shorter gestation in pre-eclamptic women.  (+info)

Long-term plasticity of endocannabinoid signaling induced by developmental febrile seizures. (53/310)

Febrile (fever-induced) seizures are the most common form of childhood seizures, affecting 3%-5% of infants and young children. Here we show that the activity-dependent, retrograde inhibition of GABA release by endogenous cannabinoids is persistently enhanced in the rat hippocampus following a single episode of experimental prolonged febrile seizures during early postnatal development. The potentiation of endocannabinoid signaling results from an increase in the number of presynaptic cannabinoid type 1 receptors associated with cholecystokinin-containing perisomatic inhibitory inputs, without an effect on the endocannabinoid-mediated inhibition of glutamate release. These results demonstrate a selective, long-term increase in the gain of endocannabinoid-mediated retrograde signaling at GABAergic synapses in a model of a human neurological disease.  (+info)

Systemic cytokine responses in patients with influenza-associated encephalopathy. (54/310)

Influenza-associated encephalopathy, a severe neurologic complication of influenza, is being reported more frequently in Japan. We investigated the transcription of cytokine genes in peripheral blood leukocytes and compared patients with influenza and with encephalopathy or febrile convulsions and patients with influenza but without neurologic complications. A quantitative polymerase chain reaction (PCR) revealed that transcription of the interleukin (IL)-6, IL-10, and tumor necrosis factor-alpha genes was up-regulated to a greater extent in patients with encephalopathy than in those without neurologic complications. Plasma IL-6 levels also were higher in patients with encephalopathy, although the difference was marginal. Viral RNA in throat swabs was quantified using a real-time quantitative PCR. The virus load was similar among patients with encephalopathy or febrile convulsions or without neurologic complications. Furthermore, virus load was not correlated with either the transcription of cytokine genes or plasma cytokine concentrations. These results suggest that influenza-associated encephalopathy might be a consequence of systemic immune responses.  (+info)

Hippocampal abnormalities after prolonged febrile convulsion: a longitudinal MRI study. (55/310)

Mesial temporal sclerosis (MTS) is the most common lesion in patients who require epilepsy surgery, and approximately 50% of patients with MTS have a history of prolonged febrile convulsion (PFC) in childhood. The latter led to the hypothesis that convulsive status epilepticus, including PFC, can cause MTS. Our recently published data on children investigated within 5 days of a PFC showed that children investigated by MRI within 48 h of a PFC had large hippocampal volumes and prolongation of T2 relaxation time. Patients investigated >48 h from a PFC had large hippocampal volumes and normal T2 relaxation time. These data are strongly suggestive of hippocampal oedema that is resolving within 5 days of a PFC, but do not exclude the possibility of a pre-existing hippocampal lesion. Fourteen children from the original study had follow-up investigations carried out 4-8 months after the acute investigations. Of the 14 patients, four have had further seizures. Two had short febrile convulsions, one had PFC and one had non-febrile seizures. There was a significant reduction in hippocampal volume and T2 relaxation time between the first and second investigations, and there is now no difference in hippocampal volume or T2 relaxation time in patients compared with a control population. Moreover, there is a significant increase in hippocampal volume asymmetry in patients at follow-up when compared with initial data. Five out of 14 patients had asymmetry outside the 95th percentile for control subjects and, of these, three had one hippocampal volume outside the lower 95% prediction limit for control subjects. A reduction in hippocampal volume or T2 relaxation time, into or below the normal range between the first and second scans, indicates that the earlier findings are temporary and are strongly suggestive of hippocampal oedema as the abnormality in the initial investigations. The change in hippocampal symmetry in the patient group is consistent with injury and neuronal loss associated with a PFC, especially in the three individuals who now have a single small hippocampus. However, as there is no T2 relaxation time abnormality, the hippocampi do not meet the criteria for MTS. There may be a lag period of several years between a PFC and the onset of epilepsy, and therefore some of these patients may be developing MTS. Alternatively, the asymmetry could represent return (post-acute oedema) to a pre-existing hippocampal abnormality similar to that identified in family members of patients with MTS and a history of PFC.  (+info)

Management of febrile convulsion: scene in a regional hospital. (56/310)

OBJECTIVE: To determine whether practice parameters are applied to the management of children with febrile convulsion. DESIGN: Retrospective study. SETTING: Paediatric department of a public hospital, Hong Kong. METHODS: Practice parameters of the American Academy of Pediatrics and audit measures recommended by the Joint Working Group of the Research Unit of the Royal College of Physicians and the British Paediatric Association were employed as standards. Records between January and April 2000 with the diagnostic coding of febrile convulsion, convulsion, status epilepticus, or meningitis/encephalitis/encephalopathy were reviewed. Areas assessed were appropriate documentation of hospital records and unit statistics (adverse outcomes, inappropriate investigations and treatment). RESULTS: Ninety-four consecutive records were evaluated. In the documentation of hospital notes, accurate description of seizure was observed in 92%, incorrect diagnosis or coding in 12%, and presence/absence of signs of meningitis and parental counselling documented in 64% and 85%, respectively. Regarding unit statistics, investigations performed included a complete blood count, blood glucose, serum calcium, serum electrolytes, renal function tests, liver function tests, chest X-ray, and urinalysis. The mean number of routine investigations was seven. The average length of stay was 2 days. There were no cases of delay in the diagnosis of central nervous system infection. Inappropriate investigations and treatment were as follows: electroencephalography 11%, computed tomography brain scan 2%, and maintenance anticonvulsants 2%. All patients were discharged home with panadol regardless of clinical state. CONCLUSIONS: The present study showed that the use of unnecessary investigations was common. Investigations, though resulting in significant expense, proved to be of little diagnostic value. Diagnostic procedures should be performed only when specifically called for by the patient's condition or medical history.  (+info)