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Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Electroencephalographic activity of the frontal cortex, cerebellar vermis, and superior vestibular nucleus was recorded in awake rats during the high pressure nervous syndrome (HPNS) by means of permanently implanted electrodes. Power-spectrum analysis revealed a decline in the faster frequencies and an increase in the slow frequences as the seizure end-point was approached. Effects of compression to 4500 fsw varied from severe tremor and myoclonic jerks to status epilepticus, with seizures occurring at an average depth of 3560 fsw. In all animals, multifocal-spiking activity progressed in severity with increasing depth. The predominant seizure pattern observed was a spike and slow-wave pattern reminiscent of absence seizures. Initial evidence of generalized seizure activity was equally divided between the cerebellum and cortex. It is concluded that the cerebellum participates in HPNS seizures. Possible evolution of the syndrome by loss of Purkinje cell inhibitory influence on subcortical sites that modulate cortical excitability is discussed.
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PMID:Cerebellar and cerebral electroencephalogram during the high pressure nervous syndrome (HPNS) in rats. 60 10

The onset of sustained multiple unit activity (MUA) in corticofugal axons was found to precede the onset of tonic EEG activity in 91 of 92 seizures produced by administering pentylenetetrazol, strychnine, or dieldrin to cats. Latency differences from 0-8 sec were observed with a mean of 3 sec. A trend was noted for shorter latencies with subsequent seizures in the same subject. No differences in latency were seen for spontaneous as compared to evoked seizures. Much variation was encountered in the pattern of MUA and EEG development at seizure onset. In general seizures with well-defined EEG components of desynchronization, tonic and clonic activity had the greatest latency differences and the least correspondence between MUA and EEG. Seizures with the abrupt emergence of tonic or clonic activity had the smallest latency differences and the best correspondence between MUA and EEG. Large changes in the activity along corticofugal axons were observed without EEG correlates. The evidence supports the concept that the degree of synchrony within the cortical (pyramidal) cell population is critical to the emergence and development of EEG during the tonic and clonic phases of a seizure. The data suggest that, in some cases, important changes in corticofugal output may contribute to and reinforce the activity in subcortical loci implicated in generalized seizure onset.
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PMID:Correlations between EEG and multiple unit activity of cortifugal axons at the onset of drug induced seizures in cats. 62 65

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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PMID:Etiology of convulsions in neonatal and infantile period. 99 19

Daily unilateral electrical stimulation of amygdala in forebrain bisected cats provoked the development of the final stage of the kindled convulsion with remarkable rapidity regardless of presence or absence of anterior commissure. The chronological and spatial pattern of propagation of afterdischarge, interictal spike discharge, and clinical manifestations strongly suggest the significant role played by the midbrain reticular formation and possibly other brainstem structures in the progressive electroclinical seizure development. This assumption was supported by the results of a lesion study in which placement of a destructive lesion in the ipsilateral midbrain reticular formation markedly increased the generalized seizure triggering threshold, lateralized the afterdischarge to the stimulated hemisphere when induced with increased intensity stimulation, fragmented clinical seizure manifestations, and failed to produce progression of clinical and electrographic events with prolonged daily stimulation. This is in contrast to the insignificant effect produced by a peduncular lesion. Our findings suggest that vertical (limbic-brainstem), but not horizontal (transhemispheric interlimbic) connection is critically involved in the amygdaloid seizure development while the forebrain commissures may play a role in the development of bisynchronous and bisymmetrical ictal and interictal electrographic and clinical manifestations. Finally, possible differential effect of forebrain bisection depending on developing in contrast with a established (cerebral) hemispheric epileptogenic process is postulated to explain the "facilitatory" effect observed in our series in contrast to the beneficial effects reported on some intractable seizure patients.
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PMID:The generalized convulsive seizure state induced by daily electrical stimulation of the amygdala in split brain cats. 118 18

Daily stimulation of the amygdala in cats resulted in progressive development of electroclinical seizures culminating in a generalized convulsion (kindling). An electrolytic lesion in the midbrain reticular formation, ipsilateral to the stimulated amygdala, markedly elevated the generalized seizure-triggering threshold and reduced susceptibility to pentylentetrazol challenge. In contrast, globus pallidus lesions had no appreciable effect upon the generalized seizure-triggering threshold and appeared to enhance susceptibility to pentylentetrazol. The results support the hypotheses that (1) the midbrain reticular formation participates significantly in the kindled amygdaloid seizures and (2) the effects of lesions in the midbrain reticular formation do not depend upon the presence of forebrain bisection.
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PMID:Effects of unilateral lesion in the midbrain reticular formation on kindled amygdaloid convulsion in cats. 122 45

Serotonin (5-HT) has been considered to possess an inhibitory action against the kindling development, but the role of 5-HT in kindled seizures is unclear. Furthermore, most previous studies have dealt with amygdaloid kindling. To clarify the role of the 5-HT system in epilepsy, we examined the effects of 5-hydroxytryptophan (5-HTP), a precursor which elevates brain 5-HT, and 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT), a 5-HT 1 a receptor agonist, on seizures kindled from the feline hippocampus (HIP). Following the completion of HIP kindling, five cats received 0.9% saline, 5-HTP (20 or 40 mg/kg, i.p.) or 8-OH-DPAT (0.1 or 1.0 mg/kg, i.v.). Drugs were administered 15 min (8-OH-DPAT) or 1 hr (5-HTP) prior to electrical stimulation at the generalized seizure triggering threshold, and the anticonvulsant effects were assessed by the behavioral seizure stage and afterdischarge (AD) duration. Both 5-HTP and 8-OH-DPAT suppressed dose-dependently HIP-kindled seizures. The administration of 5-HTP at 40 mg/kg and of 8-OH-DPAT at 1.0 mg/kg produced a marked or complete suppression of HIP-kindled seizures in most of the cats tested, and was found to significantly reduce the seizure stage when compared with the saline control. Both drugs tended to shorten the AD duration, but this effect did not reach statistically significant levels. The present data suggest that the 5-HT system plays an important role in HIP-kindled seizures, and that the 5-HT 1 a receptors have an inhibitory effect on the kindled focal epileptic activity of the HIP.
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PMID:[Serotonergic mechanisms in hippocampal kindled seizures--inhibitory effects of L-5-hydroxytryptophan and 8-hydroxy-2-(di-n-propylamino)tetralin]. 129 23

Epilepsy is analysed on terms of two different conditions, seizure susceptibility and seizure induction. Reports on detailed changes of seizure-triggering threshold and after discharge duration in seizure susceptibility are few. We examined staged changes of seizure-triggering threshold and after discharge duration in seizure susceptibility in a cat amygdaloid kindling model. Ten crossed adult cats were used. We investigated after discharge threshold (ADT), partial seizure threshold (PST) in stage 4 group (P) and generalized seizure threshold (GST) in stage 6 group (C). At the same time, we examined after discharge duration on electroencephalograph (EEG) in each stage. Seizure-triggering threshold decreases significantly step by step. After discharge duration increases significantly step by step. It is concluded that staged decrease of seizure-triggering threshold and increase of seizure's grade and duration was seen in seizure susceptibility.
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PMID:[Changes in seizure-triggering threshold and after discharge duration in seizure susceptibility]. 129 30

The level of the mRNAs encoding the AMPA-selective glutamate receptors-A and -B, alternatively splice variants, Flip and Flop, was studied by in situ hybridization in the brains of rats kindled by Schaffer collateral/commissural-fiber stimulation. In comparison to control animals, the expression level of the Flip variant of both GluR-A and GluR-B mRNAs was bilaterally enhanced in the dentate granule neurons of kindled animals 24 h after last-generalized seizure, whereas no obvious alterations were observed in the GluR-A Flop and GluR-B Flop mRNA variants. In kindled animals, studied 1 month after the last seizure, GluR-A Flip and GluR-B Flip mRNA had returned to control levels. We suggest that these changes may result in an enhanced glutamate receptor sensitivity in the fascia dentata during kindling.
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PMID:Hippocampal kindling increases the expression of glutamate receptor-A Flip and -B Flip mRNA in dentate granule cells. 130 May 3

A sensitive method of estimation of generalized seizure thresholds (GSTs) was used to estimate the relative anticonvulsant potencies of four competitive NMDA antagonists against fully amygdala-kindled seizures. All of the antagonists tested showed potent, dose-dependent anticonvulsant activity following focal administration at doses causing no, or only minimal, overt behavioural abnormalities. These doses were similar to those which have previously been shown to inhibit the development of the kindling process i.e. which show antiepileptogenic activity. Two novel, competitive NMDA antagonists, CGP 37849 and CGP 39551, both unsaturated analogues of the NMDA antagonist AP5, showed by far the greatest anticonvulsant potencies (211-fold and 33-fold greater activity than the parent molecule, respectively). Recent reports of oral anticonvulsant activity of these two compounds in both rodent and primate models of epilepsy (12, 13) make them leading candidates for clinical testing as novel antiepileptic agents in man. Previous reports of weak or non-existent anticonvulsant activity of competitive NMDA antagonists in the kindling model of epilepsy most likely result from the use of experimental protocols which are inherently insensitive in detecting drug-induced changes in seizure thresholds.
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PMID:Competitive NMDA receptor antagonists raise electrically kindled generalized seizure thresholds. 135 42

We investigated the effects of different injection intervals, (24 hr, 48 hr, and 72 hr) on the development of kindled seizures induced by repetitive pentylenetetrazol (PTZ) injections (30 mg/kg) in rats. Regardless of injection interval, kindled seizures were obtained 1 week after the completion of consecutive PTZ injections. This PTZ kindled seizure model appears to mimick generalized seizure and be useful in the investigation of seizure phenomenon. With 48 and 72 hr injection interval, the seizure responses gradually increased with consecutive injections. The convulsive severity of 24 hr interval group showed a transient increased and then stabilized at a low score (2/6). This difference between these injection interval might reflect the appearance of some short of inhibition during the more closely spaced (24 hr) repeated injections.
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PMID:Effects of injection interval on pentylenetetrazol (PTZ) kindled seizures in rats. 136 55


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