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PubMed2005

Behavioral differences between subgroups of rats with high and low threshold to clonic convulsions induced by DMCM, a benzodiazepine inverse agonist.

In epileptic patients, there is a high incidence of psychiatric comorbidities, such as anxiety. Gamma-aminobutyric acid (GABA) ionotropic receptor GABA(A)/benzodiazepine allosteric site is involved in both epilepsy and anxiety. This involvement is based on the fact that benzodiazepine allosteric site agonists are anticonvulsant and anxiolytic drugs; on the other hand, benzodiazepine inverse agonists are potent convulsant and anxiogenic drugs. The aim of this work was to determine if subgroups of rats selected according to their susceptibility to clonic convulsions induced by a convulsant dose 50% (CD50) of DMCM, a benzodiazepine inverse agonist, would differ in behavioral tests commonly used to measure anxiety (elevated plus-maze, open field) and depression (forced swimming test). In the first experiment, subgroups of adult male Wistar rats were selected after a single dose of DMCM and in the second experiment they were selected after two injections of DMCM given after an interval of 1 week. Those rats presenting full clonic convulsions were termed Low Threshold rats to DMCM-induced clonic convulsions (LTR) and those not having clonic convulsions High Threshold rats to DMCM-induced clonic convulsions (HTR). In both experiments, only those rats presenting full clonic convulsions induced by DMCM and those not showing any signs of motor disturbances were used in the behavioral tests. The results showed that the LTR subgroup selected after two injections of a CD50 of DMCM spent a significantly lower time in the open arms of the elevated plus-maze and in the off the walls area of the open field; moreover, this group also presented a higher number of rearings in the open field. There were no significant differences between HTR and LTR subgroups in the forced swimming test. LTR and HTR subgroups selected after only one injection of DMCM did not differ in the three behavioral tests. To verify if the behavioral differences between HTR and LTR subgroups of rats selected after two injections of DMCM were due to the clonic convulsion, another experiment was carried out in which subgroups of rats susceptible and nonsusceptible to clonic convulsions induced by a CD50 of picrotoxin, a GABA(A) receptor channel blocker, were selected and submitted to the elevated plus-maze and open field tests. The results obtained did not show any significant differences between these two subgroups in the elevated plus-maze and open field tests. In another approach to determine the relation between fear/anxiety and susceptibility to clonic convulsions, subgroups of rats were selected in the elevated plus-maze as more or less fearful/anxious. The CD50 for clonic convulsions induced by DMCM was determined for each of these two subgroups. The results showed a significantly lower CD50 for the more fearful/anxious subgroup, which means a higher susceptibility to clonic convulsions induced by DMCM. The present findings show a relation between susceptibility to clonic convulsions and fear/anxiety and vice versa which may be due to differences in the assembly of GABA(A)/allosteric benzodiazepine site receptors in regions of the brain.

Animals↗
PubMed1988

Evidence that alterations in gamma-aminobutyric acid and acetylcholine in rat striata and cerebella are not related to soman-induced convulsions.

Many reports have suggested that gamma-aminobutyric acid (GABA) may play a role in organophosphate-induced convulsions. The balance between GABA and acetylcholine (ACh) in the brain also has been suggested by some investigators to be related to brain excitability. We examined these questions by studying the levels of GABA and ACh and the ratios of GABA to ACh in rat striata and cerebella (two major motor control areas in the CNS) after the administration of soman, an organophosphate acetylcholinesterase inhibitor also known as nerve gas. Male Sprague-Dawley rats weighing 250-300 g were injected subcutaneously with three different doses of soman: a subconvulsive dose of 40 micrograms/kg (approximately 30% of the ED50 for convulsions in rats), a convulsive dose of 120 micrograms/kg (approximately one ED50 for convulsions), and a higher convulsive dose of 150 micrograms/kg (approximately 120% of the ED50 for convulsions). The incidence and severity of convulsions were monitored in individual rats until they were sacrificed by focused microwave irradiation of the head at the following time points after soman administration: 4 min, a time prior to the onset of convulsions; 10 min, the time of onset of convulsions; 1 h, the time of peak convulsive activity; and 6 h, a time at which rats were recovering from convulsions. Results showed that in rat striata and cerebella, neither changes in levels of GABA and ACh nor changes in ratios of GABA to ACh were related to soman-induced convulsions, i.e., none of the changes in either levels or ratios of these two neurotransmitters were related to the initiation of, maintenance of, or recovery from soman-induced convulsions.

Acetylcholine↗
PubMed1984

[Postoperative convulsion on the long-term follow-up in aneurysmal surgery].

There is some controversy in the long-term use of anticonvulsants for all postoperative cases. In order to establish the appropriate use of anticonvulsants, postoperative convulsion was studied concerning its incidence, onset and relevance with site of aneurysm, focal neurological deficits, CT findings and anticonvulsants in 169 cases of aneurysmal surgery under surgical microscope in the period of 1 to 11 years postoperatively. Convulsion was noted in 26 cases among 169 cases, and convulsion more than 1 week after operation (late convulsion) was noted in 20 cases (11.8%). Onset of late convulsion was most common during 6 to 12 months after operation and in 90 percent of cases it was developed within 2 years. In 2 of 5 cases with convulsion within 1 week late convulsion developed. On the site of aneurysm, middle cerebral artery aneurysmal cases showed high occurrence (20.5%) without statistical significance. Focal neurological deficit was one of predisposing factors for late convulsion with statistical significance (29.8%). On CT, 8 of 9 studied cases of late convulsion showed focal low density area involving cortex, although this was also noted in the cases without convulsion. Occurrence of late convulsion was significantly low (6.5%) in the cases without anticonvulsants. This suggests that there is low risk of late convulsion in the cases of uneventful postoperative course, no focal neurological signs and no abnormal findings on CT, even without anticonvulsants. Late convulsion occurred in about one third of cases treated with anticonvulsants. This is probably due to high risk and poor control of anticonvulsants plasma levels in some cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

Swim stress alters the behavioural response of mice to GABA-related and some GABA-unrelated convulsants.

To elucidate the relationship between stress and seizures, the effect of a single swim stress on the convulsive signs and death produced by several GABA-related and GABA-unrelated convulsants, and the effect of repeated swim stress on picrotoxin-induced convulsions was studied. Mice were subjected to swim stress (10 min swimming at 18-19 degrees C), and the i.v. infusion of convulsants started 15 min thereafter. The latency to the onset of several convulsant signs and death was measured, and the doses of convulsants producing convulsions and death were calculated. Additional experiments included mice swimming at room temperature, and those which were stressed repeatedly (twice a day for four consecutive days, plus one stressful procedure on the fifth day). Swim stress increased the dose needed to produce convulsant signs and death after bicuculline, picrotoxin, pentylenetetrazole, strychnine and 4-aminopyridine, while kainic acid-induced convulsions were not affected. Using picrotoxin infusion, the effect of swimming in room temperature water was less than the effect of swimming in 18-19 degrees C water. In addition, the effect of repeated stress was less than the effect of acute stress on picrotoxin-induced convulsions. The results demonstrate that acute swim stress lowers the convulsive potency of GABA-related and some GABA-unrelated convulsants. Repeatedly stressed animals develop tolerance to anticonvulsive effect of swim stress.

Animals↗
PubMed2002

Comparison of receptor mechanisms and efficacy requirements for delta-agonist-induced convulsive activity and antinociception in mice.

Delta-opioid receptor-selective agonists produce antinociception and convulsions in several species, including mice. This article examines two hypotheses in mice: 1) that antinociception and convulsive activity are mediated through the same type of delta-receptor and 2) that greater delta-agonist efficacy is required for antinociception than for convulsive activity. Delta-mediated antinociception was evaluated in the acetic acid-induced abdominal constriction assay, which involves a low-intensity noxious stimulus; convulsive activity was indicated as a mild tonic-clonic convulsive episode followed by a period of catalepsy. In delta-opioid receptor knockout mice [DOR-1(-/-)], the nonpeptidic delta-agonists (+/-)-4-[(R*)-[(2S*,5R*)-2,5-dimethyl-4-(2-propenyl)-1- piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide hydrochloride (BW373U86) and (+)-4-[(R)-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N, N-diethylbenzamide (SNC80) failed to produce convulsive behavior demonstrating the absolute involvement of DOR-1 in this effect. In NIH Swiss mice expressing delta-opioid receptors, BW373U86 produced both antinociception and convulsive activity. These effects were antagonized by the putative delta(1)-receptor-selective antagonist 7-benzylidenenaltrexone and the putative delta(2)-receptor-selective antagonist naltriben. Tolerance developed to both the convulsive and antinociceptive effects of BW373U86. Tolerance to the convulsive, but not the antinociceptive, effects of BW373U86 was largely prevented when the antagonist naltrindole was given 20 min after each dose of the agonist in a 3-day treatment paradigm. The convulsive action of BW373U86 was also less sensitive than the antinociceptive action to treatment with the irreversible delta-antagonist naltrindole isothiocyanate. Collectively, these data suggest that the convulsive and antinociceptive activities of delta-agonists are mediated through the same receptor but that the receptor reserve for delta-mediated convulsive activity is greater than for delta-mediated antinociceptive activity.

Analgesics↗
PubMed1998

Long-term intellectual and behavioral outcomes of children with febrile convulsions.

BACKGROUND: Hospital-based studies have reported that children with febrile convulsions have subsequent mental retardation and behavior problems. In contrast, population-based studies have reported a better outcome. METHODS: We identified 398 children with febrile convulsions among 14,676 children enrolled in the Child Health and Education Study, a national population-based study in the United Kingdom of children born in one week in April 1970. The children were comprehensively assessed at the age of 10. After excluding 16 children who had neurodevelopmental problems before their first febrile convulsion and 1 child whose case was atypical, we studied 381 children, 287 with simple febrile convulsions and 94 with complex febrile convulsions. We compared them with the rest of the cohort using measures of academic progress, intelligence, and behavior that included questionnaires, standardized tests, and formal tests. RESULTS: At the 10-year assessment, only 4 of 102 measures of academic progress, intelligence, and behavior differed significantly between the entire group of children with febrile convulsions and the group without febrile convulsions -- no more than would be expected by chance. Similar results were found when children with simple febrile convulsions and those with complex febrile convulsions were analyzed separately. The children with recurrent episodes of febrile convulsions had outcomes similar to those of the children with only one episode each. Special schooling was required for more children who had febrile convulsions in the first year of life than for those who had had them later in life (5 of 67, or 7.5 percent, vs. 4 of 265, or 1.5 percent; P=0.02), but these numbers were small. CONCLUSION: Children who had febrile convulsions performed as well as other children in terms of their academic progress, intellect, and behavior at 10 years of age.

Age Factors↗
PubMed1996

Pharmacological analysis of local anaesthetic tolycaine-induced convulsions by modification of monoamines in rat brain.

The effects of a local anaesthetic, tolycaine, on brain monoamine levels were investigated during the convulsive process in rats. The influence of central monoamine modifications on tolycaine-induced convulsions was also examined. Tolycaine (140 mg/kg, intraperitoneally) produced a significant elevation of noradrenaline and 5-hydroxytryptamine levels in all brain regions in the convulsive state from the levels in the non-convulsive state. Their levels returned to normal during the postconvulsive state. Dopamine levels were depleted in the cerebral cortex, the striatum, and the ponsmedulla oblongata during the convulsive process and increased in the cerebellum. Pretreatment with alpha-methyl-p-tyrosine, which depletes brain catecholamine, suppresses the tolycaine-induced convulsions, as shown by a decrease in the incidence; L-3,4-dihydroxyphenylalanine and bis-(1-methyl-4-homopiperazinyl-thiocarbonyl)-disulfide, which increase brain catecholamine, intensified the convulsions, as shown by shortening of the latency and increase in the mortality. Antagonists of beta-adrenergic and dopamine receptors, such as propranolol, chlorpromazine and pimozide, markedly suppressed the convulsions, but an antagonist of alpha-adrenergic receptor, phenoxybenzamine, had no effect. Furthermore, 5-hydroxytryptophan, which increases brain 5-hydroxytryptamine, suppressed the convulsions, and DL-p-chlorophenylalanine, which depletes brain 5-hydroxytryptamine, intensified them. Antagonists of 5-hydroxytryptamine receptor, methysergide and methiothepin, suppressed the convulsions. These results suggest that brain noradrenaline and 5-hydroxytryptamine are major regulators in the tolycaine-induced convulsive process and that central catecholaminergic neurones act in a stimulatory way on the tolycaine-induced convulsions, while serotonergic neurones act suppressively.

Adrenergic Agents↗
PubMedDate not supplied

[Up-date on the subject of neonatal convulsions].

New experimental, clinical and therapeutic results in the field of convulsive disorders of the newborn have recently come to light. Experimental studies on animals have shown that, contrary to what was assumed in the past, the immature brain is highly excitable, and during the first weeks of life excitation processes predominate over inhibitory processes. Over the last ten years, benign idiopathic convulsions in newborns, familial convulsions and benign convulsions on the fifth day of life, have been defined. Both types develop and disappear spontaneously during the first week of life and have a favourable prognosis, although they may appear at the start (especially the benign fifth-day convulsions) as status epilepticus. Recently, two types of convulsive status epilepticus in newborns have been identified: a severe idiopathic status epilepticus and focal status epilepticus. The myoclonic syndromes which occur during quiet sleep and which are not accompanied by EEG discharges should be distinguished from convulsions and do not require anti-convulsive therapy. The various EEG monitoring techniques have shown an unexpectedly high number of convulsions, especially in the form of sub-clinical convulsions and/or atypical convulsive seizures. The atypical seizures distinctly predominate in status epilepticus. The clinical evidence of the seizures in reduced by administration of anti-convulsants, which seem to block typical seizures and, viceversa, to be less active for atypical seizures and EEG seizures. In the therapeutic field, the use of phenobarbital and/or phenytoin at a high initial dosage (20 mg/kg) has been well affirmed. Drugs such as lidocaine and thiopental are currently being experimented and have given encouraging results in severe status epilepticus.

Animals↗
PubMed1996

Neurotoxic convulsions induced by histamine H2 receptor antagonists in mice.

Convulsive potency was evaluated to investigate the mechanism of neurotoxic convulsion induced by histamine H2 receptor antagonists (H2 blockers). Four H2 blockers, cimetidine (721-1236 nmol), ranitidine (477-954 nmol), famotidine (7.4-44 nmol), and nizatidine (226-603 nmol) were administered intracerebrally (i.c.) to mice. Dose dependency of clonic and/or tonic convulsion was observed, and the ED50 values of convulsive occurrence for cimetidine, ranitidine, famotidine, and nizatidine were 997, 662, 23.4, and 404 nmol, respectively. Intraperitoneal pretreatment of muscimol, aminooxy acetic acid, diazepam, (+/-)2-amino-7-phosphonoheptanoic acid (APH), or (+)MK801 suppressed the tonic convulsion after i.c. administration of ranitidine, but had no effect on clonic convulsion. Furthermore, the convulsive threshold concentration in the brain determined by constant rate infusion of ranitidine was not affected by the pretreatment of muscimol, diazepam, APH, and MK801. Ed50 values for convulsive occurrence after i.c. administration of four H2 blockers correlated well with the EC50 values for gastric acid secretion inhibition. The convulsive threshold concentrations of cimetidine and ranitidine in the brain were 11 and 2.5 microM, respectively, which were similar to the dissociation constants determined from the inhibition of gastric acid output in mice. From these results, tonic convulsion induced by H2 blockers can be suppressed by GABAergic or glutamatergic anticonvulsants, while clonic convulsion induced by H2 blockers may be associated with the blockade of H2 receptor in the brain and not be directly associated with the GABA and glutamate-mediated neurotransmission.

Animals↗
PubMed1997

Inhibitory effect of new quinolones on GABA(A) receptor-mediated response and its potentiation with felbinac in Xenopus oocytes injected with mouse-brain mRNA: correlation with convulsive potency in vivo.

Convulsions induced by the interaction of new quinolone antimicrobial agents (NQs) and nonsteroidal anti-inflammatory drugs (NSAIDs) were previously reported, and blockade of GABA(A) receptor by NQs and its potentiation with NSAIDs were considered as one of its possible mechanisms. However, useful methodology for prediction of convulsive potencies of NQs with or without NSAIDs in vivo based on in vitro screening was not established. Therefore, we applied the Xenopus oocytes translation system of exogenous messenger RNA (mRNA) to examine the mechanism of convulsion induced by interaction of NQs and NSAIDs, and the relationship between convulsive potencies in vivo and inhibitory effect on GABA-induced current response in vitro was investigated. This system also has alternative possibility for the in vivo toxicological studies sacrificing innumerous animals. Glutamic acid, kainic acid, quisqualic acid, NMDA, and serotonin-induced currents were not modified by ENX of NQs and/or FLB of NSAIDs, while glycine- and ACh-induced currents were slightly inhibited. GABA (10 microM)-induced current was inhibited by norfloxacin (NFLX), ciprofloxacin, ENX, and ofloxacin (OFLX) with IC50 of 17, 33, 58, and 280 microM, respectively. IC50 of NQs decreased to 1/3 (OFLX)-1/165 (NFLX) in the presence of 10 microM FLB, while FLB did not modulate the GABA response in the absence of NQs. CSF concentration of ENX at the time of convulsion in clinical situation approximated the IC50 of ENX for the GABA response. The increase of incidence for NQs-induced convulsion by concomitant NSAIDs in vivo could also be explained by the potentiation of inhibitory effects of NQs with FLB in the normal range of CSF concentration of these drugs. We also examined convulsive potency (threshold dose for convulsion) in CNS by intracerebral infusion of NQs to mice with or without FLB pretreatment, and significant correlations between the convulsive potencies and IC50 of NQs for the GABA response were observed. These findings suggested that the blockade of GABA-ersic neurotransmission in CNS is a dominant mechanism of convulsion induced by NQs and that the convulsant-adverse reaction of NQs in vivo may be predicted from the inhibitory effect on the GABA(A) receptor in vitro using the Xenopus oocytes translation system of exogenous mRNA.

Animals↗
PubMed1992

Brain norepinephrine reductions in soman-intoxicated rats: association with convulsions and AChE inhibition, time course, and relation to other monoamines.

The organophosphate chemical nerve agent, soman, causes convulsions, neuropathology, and, ultimately, death. A major problem in treating soman intoxication is that peripherally acting pharmacological agents which prevent death do not prevent seizures. Although a primary cause of these symptoms is the excess of acetylcholine which follows acetylcholinesterase (AChE) inhibition, centrally acting muscarinic blockers, such as atropine, alleviate, but do not block, the convulsive actions of soman. Moreover, there is a relatively weak relationship between CNS reductions of AChE and the incidence of convulsions. There is evidence suggesting that soman intoxication stimulates the release of norepinephrine (NE) in the brain. Recent evidence has implicated NE in the induction and/or maintenance of seizures. Thus, in the present study the relations among soman-induced convulsions, AChE inhibition, and brain NE and other monoamine changes were examined. The time course of brain NE recovery was also determined. Rats were injected (im) with a single dose (78 micrograms/kg) of soman. At this dose 68% of the injected rats developed convulsions. Both convulsive and nonconvulsive rats were sacrificed between 1 and 96 h following soman injection and NE levels in the rostral forebrain and olfactory bulb were determined by HPLC with electrochemical detection. In all convulsive rats NE levels declined substantially. Forebrain NE levels were decreased by 50% at 1 h and 70% at 2 h following soman injection. Recovery of NE began at 8 h and was complete by 96 h following soman administration. Although nonconvulsive rats showed other signs of intoxication, NE levels in these rats were unchanged. Dopamine (DA) and serotonin (5-HT) levels were not significantly affected in either convulsive or nonconvulsive rats. However, 5-hydroxyindoleacetic acid, the major metabolite of 5-HT, and homovanillic acid and 3,4-dihydroxyphenylacetic acid, the two major metabolites of DA, were increased significantly in the forebrain of convulsive, but not nonconvulsive rats, indicating an increase in 5-HT and DA turnover. However, in contrast to the abrupt decline in NE, these increases in DA and 5-HT metabolites were slow and progressive. Taken together, the present results and other recent findings suggest that rapid, sustained NE release could play a role in the induction and/or maintenance of soman-induced convulsions, whereas increased release of 5-HT and DA may be a consequence of seizures. Further investigation of the role of NE in soman-induced convulsions may lead to improved treatment of soman intoxication and a better understanding of the role of NE in other forms of seizures, including human epilepsy.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1988

Soman-induced convulsions affect the inositol lipid signaling system: potentiation by lithium; attenuation by atropine and diazepam.

Effects of atropine or diazepam pretreatment on soman-induced convulsions and brain phosphoinositide (PI) metabolism, as assessed by brain regional inositol-1-phosphate (IP1) levels, were studied in saline and LiCl-pretreated rats. IP1, an intermediate in PI turnover, was measured in cortex, caudate, thalamus, hippocampus, and cerebellum. Soman (100 micrograms/kg; sc) produced convulsions in 63% of the saline-pretreated rats, whereas with LiCl pretreatment all rats exposed to 100 micrograms/kg of soman had tonic-clonic convulsions. Thus, LiCl pretreatment potentiated soman-induced convulsions. Tissue IP1 increased severalfold in soman-exposed convulsing rats with the highest increases being in frontal cortex and caudate. In contrast, no marked increases of IP1 occurred in similarly treated nonconvulsing rats. LiCl treatment itself increased IP1 levels without causing convulsions. In LiCl-pretreated rats, soman again markedly elevated IP1 levels above LiCl alone in convulsing rats, whereas no such effect occurred in nonconvulsing rats. In LiCl-pretreated rats, the increased IP1 levels associated with soman-induced convulsions were greatest in hippocampus and piriform cortex. Thus, LiCl appears to lower the threshold for the spread of seizure activity through limbic structures, thereby potentiating cholinergic-induced convulsions. Diazepam and atropine both blocked soman-induced convulsions, and brain regional IP1 elevations were concomitantly abolished as well. These results indicate that soman-induced convulsions involve the inositol lipid signaling system. This involvement is potentiated by lithium but attenuated by atropine and diazepam.

Animals↗
PubMed2002

The crude extract from the sea anemone, Bunodosoma caissarum elicits convulsions in mice: possible involvement of the glutamatergic system.

The crude extract from the sea anemone, Bunodosoma caissarum caused dose-dependent convulsions by i.c.v. route in mice. The involvement of the glutamatergic system in the convulsions was investigated. MK-801 and ketamine, non-competitive NMDA receptor antagonists, prolonged the latencies for convulsion onset. AP-5, a competitive NMDA receptor antagonist, reduced the number of animals convulsing and also increased the latency for convulsion onset. 7-Chlorokynurenic acid, an antagonist of the glycine site on the NMDA receptor, reduced the incidence of convulsions. GMP, a nucleotide known to antagonize some NMDA actions, reduced the incidence and the severity of convulsions and prolonged the latency for their onset. Riluzole, a neuroprotective and anticonvulsant agent, blocked the appearance of convulsions. In vitro, the crude extract inhibited [3H]glutamate binding to cerebral cortical membranes and enhanced [3H]glutamate release from cortical synaptosomes. Heating the crude extract to 100 degrees C for 30 min or preincubating it with sphingomyelin, abolished its effect on glutamate release, but did not alter its ability to induce convulsions and to inhibit glutamate binding. However, the convulsant action was inhibited when the crude extract was submitted to trypsin treatment. Our data suggest that the convulsions elicited by the crude extract are not due to the presence of cytolysin and are not related to an increase in glutamate release, but seem to be dependent on the interaction between a peptide component of the extract and NMDA receptors.

Animals↗
PubMed1999

Generalized convulsive epilepsy: possible mechanisms.

Neuronal mechanisms underlying focal convulsions and secondary generalized convulsions continue to be intensively investigated and many important pathophysiological processes are now recognized. Our understanding of primary generalized convulsions remains limited in spite of a variety of approaches. While there are well known clinical situations offering insights into some aspects of the pathophysiology, studies in animal models of generalized convulsions offer a deeper understanding of some of the processes likely to be occurring. Animal studies have indicated that generalized convulsive epilepsies are likely to be comprised of several types of convulsion and that these arise from more than one neuronal network. In particular, the cortex and brain stem can interact in various ways to lead to convulsions and may even act independently. Pharmacological agents can produce specific changes in the excitability of neurons and cause generalized convulsions, so providing models of the possible neurophysiological defects in humans. Based on electrophysiological recordings of generalized convulsions in these animal models, we also suggest that the convulsion involves subcortical mechanisms and raise the idea that primary generalized convulsive epilepsy arises out of intensified (synchronized) normal brain rhythms. Copyright 1999 Harcourt Publishers Ltd.

Journal Article↗
PubMedDate not supplied

[Retrospective study of 160 children with febrile convulsions].

In a retrospective study of 411 children with cerebral convulsions over a period of 4 years, 160 patients with febrile seizures were found. This group consisted of 94 boys and 66 girls. The main purpose of this study was to establish the age of the first convulsive fit in each child. Febrile convulsions started in the first half year, increased in the second half year and culminated in the second year of life. This age dependent appearance was explained with passive immunization by maternal antibodies so that febrile convulsions appear when these antibodies decrease. The first occurrence of febrile convulsions appeared on an average of 22.9 months, in children with recurrent febrile convulsions a little earlier with 18.2 months. The most interesting fact was that children with a family history of febrile seizures showed an even earlier occurrence of the first seizure with 14.5 months. This tendency of early incidence of febrile convulsion in the group with family history and in the group of recurrent febrile convulsions could be shown as statistically significant respectively nearly significant in comparing with the group of retarded patients. A peculiar tendency for febrile convulsions seems to be documented by recurrent seizures in the patient himself, but also by a history of febrile convulsions in other family members. Both facts may lead to a very early incidence of febrile convulsions.

Age Factors↗
PubMed2002

Risk factors for febrile convulsions.

BACKGROUND: Little is known about the relative importance of genes and early environment in the etiology of febrile convulsions. METHODS: We performed a follow-up study using data from two nationwide registers in Denmark, 1980-1998. The study population comprised 10,224 younger siblings of children who had had febrile convulsions, and 21,218 younger siblings of children who had never been hospitalized with febrile convulsions. RESULTS: The study provides three main findings. First, if a previous child had had a febrile convulsion, the risk was lower for the next child if either parent changed partners. Compared with full-siblings, the hazard ratio (HR) of febrile convulsions was 0.6 for paternal half-siblings and 0.7 for maternal half-siblings. In contrast, if there was no history of febrile convulsions in the previous child, a change in partner was associated with a slight increase in risk (1.2 among paternal half-siblings and 1.3 among maternal half-siblings). Secondly, the risk of febrile convulsion was strongly associated with the number of hospitalizations for febrile convulsions experienced by the older siblings, with a doubling of risk among those whose older sibling had had three or more hospitalizations. Thirdly, the risk of febrile convulsions increased with decreasing gestational age, birth weight, and birth weight ratio regardless of family history. CONCLUSIONS: Our data suggest that the etiology of febrile convulsions depends on a genetic susceptibility that can be transmitted through both parents, and corroborates the hypothesis that multiple febrile convulsions may constitute a separate etiological entity.

Birth Weight↗
PubMed1988

Alterations in the pharmacokinetic properties of amide local anaesthetics following local anaesthetic induced convulsions.

The comparative pharmacokinetic properties of lidocaine, bupivacaine, etidocaine and mepivacaine were investigated in convulsing and non-convulsing dogs. The same dose of a given local anaesthetic was administered as either a 30-s intravenous (IV) bolus to produce convulsions or as a 15-min IV infusion producing no convulsions. Derived pharmacokinetic data were found to be different in convulsing and non-convulsing animals. Total body clearance was found to be significantly reduced for lidocaine (29%, P less than 0.05), bupivacaine (31%, P less than 0.05), etidocaine (60%, P less than 0.01) and mepivacaine (68%, P less than 0.01) in convulsing animals. Increases in elimination half-life only achieved statistical significance in mepivacaine-treated animals (non-convulsing 45.2 min, convulsing 105.4 min, P less than 0.01). Overall, the most profound effects of convulsions on pharmacokinetic data were seen with mepivacaine. Convulsions were associated with increases in heart rate ranging from 117% (lidocaine, P less than 0.05) to 129% (mepivacaine, P less than 0.05), increases in cardiac output ranging from 78% (mepivacaine) to 232% (bupivacaine, P less than 0.05) and increases in mean arterial pressure ranging from 45% (lidocaine, P less than 0.05) to 80% (bupivacaine, P less than 0.05). The results suggest that when local anaesthetic-induced seizures occur in man, it cannot be assumed that these drugs will be distributed and eliminated as predicted by intravenous infusion of non-toxic doses.

Anesthetics, Local↗
PubMed1976

Etiology of convulsions in neonatal and infantile period.

1) Etiology of convulsions starting prior to two years of age was discussed in 418 cases. Neonatal seizures before 30 days old appeared in 86 cases (53 boys and 33 girls). Three hundred and thirty-two patients (172 boys and 160 girls) had convulsions in infancy. Twelve patients (9 boys and 3 girls) suffered from convulsions both in neonatal and infantile period. 2)Etiology of convulsions was prenatal in 67 cases (16%), natal in 49 cases (12%), postnatal in 158 cases (38%) and unknown in 144 cases (34%). Prenatal factors consisted of cerebral malformation (23 cases, 6%), associated physical minor anomaly such as cataracta or finger abomaly (11 cases, 3%), abnormal pernatal history (8 cases, 2%), congenital heart disease 3) cases, 1%), tuberose scleorsis (7 cases, 2%) and positive family history (13 cases, 3%). Postnatal causes included hypocalcemia or hypoglycemia (7 cases, 2%), brain tumors (3 cases, 1%), breath-holding spells (21 cases, 5%), febrile convulsion (44 cases, 11%), bathing (3 cases, 1%), afebrile colds (3 cases, 1%), purulent meningitis (17 cases, 4%), DPT immunization (10 cases 2%), vaccination (7 cases, 2%) and acute hemiplegia (10 cases, 2%). The group of unknown etiology were as fns (38 cases, 9%), epilepsy associated with interictal signs (23 cases, 6%), benign infantile convulsions (57 cases, 14%), neonatal convulsion of unknown etiology (12 cases, 3%) and miscellaneous categories (4%). 3) Pregnancy was abnormal in 53% of cases with cerebral malformation. Asphyxia at birth was noted in 43% of patients with tuberose sclerosis and in 35% of congenital cerebral abomaly. 4) Pneumoencephalographic examinations revealed midline anomaly in 50% of cerebral malformation. It was abnormal in all cases with tuberose sclerosis, head injury and epilepsy with interseizure neurological signs. 5) There were no correlations between the seizure pattern and the etiology in neonatal convulsion. In infancy, focal-unilateral convulsions and infantile spasms were frequently associated with organic damages. Generalized seizures were seen in organic lesions as well as functional ones although approximately half of the cases were febrile convulsion, benign infantile convulsion or breath-holding spell. 6) EEG features of cerebral malformation were asymmetrical or multifocal dischages in neonatal period and hypsarhythmia or focal-unilateral spike discharges in infancy. Tuberose sclerosis showed hypsarhythmia in infancy. In birth injury or cerebral anoxia, EEG mostly revealed focal-unilateral abnormality or suppression-burst activity in newborns and hypsarhythmia or focal features in infants. 7) The occurrence rate of neonatal seizures in autopsy cases with intracranial pathology was demonstrated. EEG with intravenous diazepam was useful to know pathophysiology of infantile spasms.

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