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

In former investigations on human focal epilepsy and on experimental epilepsy by cobalt implantation, the authors have demonstrated the signaletic importance of "activated astrocytes": cortical astrocytes endowed with a modified metabolism and an accelerated turnover. The present study concerns the results of the intra-amygdaloid injections of kainic acid, a strong excitatory and neurotoxic amino acid. Injections in semi-chronic conditions in the rat lead to electrical and motor seizures and to the production of activated astrocytes not only in regions that might trigger off epileptic seizures (cerebral cortex, amygdala, possibly hippocampus), but also in the neostriatum. Stimulation of this last region results in a Huntington chorea-like syndrome. Thus, the importance of activated astrocytes must be extended to include other conditions of intense hyperactivity of neurons than epilepsy.
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PMID:[Histochemical study of central nervous system lesions in experimental epilepsy caused by kainic acid]. 732 58

Focal, secondarily generalizing, epileptic seizures were released by magnetic stimulation in a patient with focal epilepsy. The stimulation induced seizures had a similar clinical appearance to the patient's spontaneous seizures. They were released exclusively by an angulated "figure-of-8" coil which stimulates the brain more focally as compared to the commonly used flat round coil. The epileptic focus could be located in the left frontal cortex by electroencephalographic recordings, by magnetic resonance and by positron emission tomography imaging. Functional assessment of the motor system by transcranial magnetic stimulation (TMS) disclosed markedly prolonged electrical silence of contralesional electromyographic activity following the early excitation. This is the first EMG-documented demonstration of a focal motor seizure directly triggered by magnetic brain stimulation.
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PMID:Epileptic seizures triggered directly by focal transcranial magnetic stimulation. 753 Jun 36

The initial objective of the present study was to investigate the role of excitatory and inhibitory amino acids in generalized as compared to focal epilepsy, both forms being induced by the same convulsant agent, i.e. penicillin. Our attempts to obtain in the rat the generalized epilepsy, constantly induced in cats by systemic administration of penicillin, were unsuccessful. This is probably due to the rudimentary development of the cerebral cortex in rodents as compared to the feline cortex. The tentative conclusion was drawn that the cortex is the brain structure mainly involved in the genesis of petit mal seizures. Penicillin was applied to the cortex of 40 white Wistar rats and the electrical cortical activity was registered. The concentrations of glutamate, aspartate, glycine, GABA and serine were determined in the cerebral cortex, the brain stem and the cerebellum. The same amino acids were determined in the brain of 20 controls. No significant changes in the amino acid contents were obtained in the cerebral cortex. In the brain stem the glutamate level was significantly increased while the glycine content was markedly decreased. These findings are consistent with the involvement of the brain stem structures in seizure activity.
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PMID:Amino acid content of the brain in rats focal penicillin induced epilepsy. 754 74

The distribution of Fos protein was mapped in rat brain following a single non-focal convulsive seizure. Single seizures were induced with intravenous picrotoxin in unhandled animals housed in isolation. Different convulsive behaviours occurred unpredictably. The least severe seizures were predominantly localised to the face, head and forelimbs, without loss of posture control (restricted seizures). The most extensive seizures affected all limbs and trunk, sometimes with falling (generalised seizures). There was a correlation between seizure behaviour and distribution of Fos induction. After restricted seizures, Fos was induced at highest levels in neocortex and piriform cortex and was prominent in entorhinal cortex, caudal-ventral caudate-putamen and amygdala. Regions of thalamus were consistently and lightly labelled, but Fos induction did not occur in hippocampus. After generalised seizures, there was Fos induction in cortex but less than after restricted seizures and, in three of four animals, also in dentate gyrus, hippocampus and subiculum. There was occasional or variable labelling of thalamus, basolateral amygdala and caudate-putamen. One animal with generalised seizures showed no hippocampal Fos induction. The findings indicate that picrotoxin induces seizures with at least two different patterns of neuronal involvement. The cortex, part of the caudate-putamen, amygdala and thalamus are involved in restricted seizures while the hippocampus, cortex and thalamus are involved in generalised seizures. The results do not support the view that generalised seizures are a progression from restricted forms. Cortical Fos involvement is entirely consistent with the participation of cortex in non-focal epilepsy. In these non-focal seizures, the dentate-hippocampus may be a source of excitation to cortex in the generalised group while the cortex appears to be the predominant site of excitation in the restricted group.
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PMID:Distribution of Fos-positive neurons in cortical and subcortical structures after picrotoxin-induced convulsions varies with seizure type. 755 47

Functional magnetic resonance imaging (fMRI) with susceptibility-based contrast was used to detect focal changes in cerebral blood flow and metabolism in a patient with focal epilepsy. The patient presented with frequent partial motor seizures involving his right lower face that spread to produce speech arrest and occasionally right arm jerking. Consciousness was never impaired during these events. A multislice echoplanar technique was used to acquire 16 contiguous axial slices every 4 seconds for 11 minutes. Although no overt seizures were observed or reported by the patient during the scanning, a time series analysis of the functional data revealed focal signal-intensity changes in the posterior left frontal lobe, which correlated well both in duration and spatial localization with ictal activity subsequently recorded by invasive electrophysiological monitoring. The spatial localization of fMRI was more accurate than electroencephalography recorded from a subdural grid in predicting the site of successful surgical therapy. These results illustrate the potential of functional MRI for localizing seizure foci with high spatial and temporal resolution. Such studies can be readily combined with high-resolution anatomical imaging, task-activation studies, and other magnetic resonance techniques.
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PMID:Localization of subclinical ictal activity by functional magnetic resonance imaging: correlation with invasive monitoring. 757 58

Lamotrigine (LTG) has recently been approved for marketing in Australia as add-on therapy in resistant partial seizure disorders. Early reports cited a therapeutic blood level for LTG of 1-3 mg/L (4-12 mumol/L). Aspects of routine patient care with LTG, devoid of the restrictions of trial protocols, are discussed. Forty-five patients commenced therapy but 15 discontinued LTG. Of the remaining 30 patients, 9 became seizure free, 3 from the de novo trial in focal epilepsy and 6 with generalised epilepsy. Global evaluation of patients showed mild to moderate improvement for those with focal epilepsy and moderate to marked improvement for those with generalised epilepsy. Blood levels of LTG did not provide clinically useful information.
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PMID:Routine use of lamotrigine, a new anti-epileptic medication, and the value of measuring its blood levels. 758 66

A 9-year-old right-handed girl was admitted because of complex partial seizures, left-right disorientation and finger agnosia. At the age of 2 years, she began to have seizures, which were exacerbated by carbamazepine and diazepam. Subsequently she was treated with phenytoin and phenobarbital, and remained seizure-free for four years. After age 7, she began to have attacks of alteration of consciousness, which lasted 10 seconds and occurred every two or three months. At age 9, neuropsychological testing revealed borderline intellectual functioning (WISC-R:FSIQ 83, VIQ 94, PIQ 73), but selective deficits were found in tests of calculation and spatial-figural relationships. Axial spin echo (3,000/22) image showed an abnormal high signal intensity in the left temporo-parieto-occipital lobe, in which interictal IMP-SPECT demonstrated decreased cerebral blood flow. These results seemed to explain the relationship between clinical findings and focal migration disorder. It is important to detect a focal migration disorder in patients with intractable focal epilepsy or higher cortical dysfunctions.
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PMID:[Higher cortical dysfunctions and image diagnosis in a 9-year-old girl with complex partial epilepsy caused by focal neural migration disorder]. 761 91

Between 1982 and 1991, 11 patients (4 male, 7 female) ranging in age from 16 to 42 years who had been diagnosed with idiopathic focal epilepsy resistant to medication, were treated with stereotactic radiosurgery. The preoperative symptomatic period was 3-24 years. The process of localizing epileptic focus was based on chronic electrocorticography with flexible electrodes introduced into the subarachnoid space through single burr holes, and left in place during a maximum of 7 days until a clinical seizure was recorded. In most cases the procedure had to be repeated until localization was clear. This process was aided by a computer-assisted automatic analysis procedure. Final confirmation of focus location was done with depth electrode recording in most cases. Stereotactic radiosurgery was performed with a 60Co gamma source using 10 mm collimators, except in two cases in which a betatron was used. The estimated dose was 10-20 Gy at the isocenter. Four of the 11 patients (36%) were medication- and seizure-free after a mean follow-up of 102.5 months. Five patients (45%) presented a reduction of seizures of 98, 89, 86, 75 and 75%, respectively. Two patients did not respond to treatment. Seizure reduction began after a delay period of 2-12 months except in 2 patients and in most cases seizure rate decreased progressively during several months (range: 3-48) postoperatively until stabilization. No complications related to irradiation were recorded. Doses effective for epilepsy are much lower than those for producing cerebral lesions, so the mechanism is not destruction of the focus of the pathways spreading the epileptic activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stereotactic radiosurgery may be effective in the treatment of idiopathic epilepsy: report on the methods and results in a series of eleven cases. 762 46

Often, seizures in childhood are intractable to medical therapy. Intractable seizures and prolonged anticonvulsant medication can adversely affect intellectual development and psychosocial maturation in children. Temporal lobe resections for complex partial seizures and focal epilepsy in children can be performed with minimal morbidity. The higher morbidity lies with prolonged observation of these children with intractable seizures. The final result of surgical treatment shows that children can significantly benefit from an early developmental period without anticonvulsant medication or intractable seizures with improvements in both IQ and behavioral interactions. With improvements in neuroimaging techniques and evaluation procedures, more children can be identified who might benefit from a resective procedure. It is thus advocated that early evaluation and surgical intervention be performed to gain improvement in seizure control and psychosocial development.
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PMID:Temporal lobe resections in children. 767 Mar 25

Mutant epileptic E1 mice are thought to have focal epilepsy of hippocampal origin because glucose utilization is increased in the hippocampus (HPC) during seizures in these mice. However, direct electrographic evidence is still lacking for the notion. We recorded electroencephalograms (EEGs) using depth electrodes in E1 and non-epileptic ddY mice. All the mice were subjected to a conventional seizure-provoking maneuver during EEG recording; each mouse was placed on a mesh floor and observed for 3 min, and then tossed up in the air. When the E1 mice showed signs of abortive seizures or prodromal symptoms including squeaking, running and myoclonus, sporadic spikes or sharp waves were generated exclusively in the HPC. When generalized convulsions followed these prodromes, the sporadic discharges evolved into a burst of generalized spikes which again predominated in the HPC. We also observed the cerebral cortex, amygdaloid, caudate, centro-median thalamic and ventral postero-lateral thalamic nuclei, all of which were found to be only secondarily involved. These findings provide the first electrical evidence that E1 mice have a secondarily generalized seizure that has its initiating focus in the HPC.
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PMID:Depth EEG in mutant epileptic E1 mice: demonstration of secondary generalization of the seizure from the hippocampus. 768 Sep 97


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