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

The waveform morphology of interictal spike activity associated with uncontrolled childhood focal epilepsy was quantified in 40 patients by a computer-based technique. The findings were then analyzed with respect to epileptic syndromes. Samples of spike activity from each patient were characterized by determination of average amplitude (A), duration (D), and sharpness (S). A single morphologic index, the composite spike parameter (CSP), was also derived from the basic spike parameters (CSP = A x D/S). The spikes of patients in the benign focal epilepsy category differed from those of patients in other syndromic categories (symptomatic, cryptogenic, and Landau-Kleffner). Specifically, they were higher in amplitude, longer in duration, less sharp, and had a higher CSP value. The pretreatment spike parameters did not differ significantly in patients who responded favorably to initial antiepileptic drug (AED) therapy as compared with those whose seizures were harder to control. The findings suggest that quantitative assessment of interictal spike morphology may help develop a more objective basis for classifying patients according to epileptic syndrome.
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PMID:Spike morphology in childhood focal epilepsy: relationship to syndromic classification. 159 33

Penfield's observations in the 1930s provided the first systematic evidence of changes in regional cerebral blood flow (rCBF) associated with focal seizures. Further studies in humans and animals confirmed increases in cerebral blood flow and metabolism during generalised seizures, but the interictal, ictal, and postictal changes in focal epilepsy have begun to be elucidated in the last decade with the advent of in vivo imaging techniques such as positron emission tomography (PET) and single photon emission computed tomography (SPECT) and, in the case of animal studies, of autoradiography. Most studies have been of temporal lobe epilepsy. Interictally, the characteristic finding has been reduced blood flow and/or metabolism in the affected temporal lobe, or more extensively in the ipsilateral hemisphere. The few studies to date of ictal or postictal changes have been of rCBF using SPECT. They show hyperperfusion of the whole temporal lobe ictally, hyperperfusion of the hippocampus, combined with hypoperfusion of lateral structures in the immediate postictal period. Later in the postictal period, hypoperfusion alone is seen. Studies of focal seizures in animals have shown hyperperfusion and hypermetabolism at the site of the focus often with widespread depression of both parameters in the ipsilateral neocortex. Limited studies of coupling between blood flow and metabolism in humans have suggested that flow during seizures is adequate for metabolic demand, although some animal studies have suggested localised areas of uncoupling. The results of modern in vivo imaging of ictal and postictal changes in blood flow and metabolism have correlated well with Penfield's observations, and these changes are now being used to help localise epileptic foci, allowing wider use of the surgical treatment he pioneered.
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PMID:Epilepsy, cerebral blood flow, and cerebral metabolic rate. 162 38

Severe persistent neuropsychological disorders sometimes develop in the course of a focal epilepsy of unknown origin in previously normal children. Very frequent bilateral focal or generalized discharges are often noted on the sleep EEG records of these patients with no evidence of clinical seizures. The relation between these paroxysms and the observed deterioration remains unclear. We report a child with a partial complex epilepsy and severe disturbances of language, cognition, and behavior acquired in the early years of development who was followed for 15 years. A correlation between the evolution of the striking EEG abnormalities during sleep and the neuropsychological disorders could be established retrospectively. The observed sequence of onset and recovery of the aphasia, the dementia, and the "psychotic" behavior makes a direct causal relation between the deficits quite unlikely. Rather it suggests an association of independent symptoms with a specific language disorder becoming manifest in the course of the evolution. This child shows many of the main characteristics of the syndromes of "acquired aphasia with convulsive disorder" (Landau-Kleffner syndrome) and "epilepsy with continuous spike waves during sleep." Both syndromes describe probably different facets of a similar underlying, still unexplained cerebral dysfunction.
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PMID:Acquired aphasia, dementia, and behavior disorder with epilepsy and continuous spike and waves during sleep in a child. 171 72

Wilder Penfield's development of surgical methods for treating focal cerebral seizures, beginning with his early work in Montreal in 1928, is reviewed. The reliance on seizure pattern and focal brain pathology was enormously enhanced by the advent of EEG and direct electrical recording from the cortex during surgery. The recognition in the early 1950's of mesial temporal structures in the pathogenesis of temporal lobe epilepsy with automatism lead to more rational and successful surgical treatment. Positron emission tomography and especially magnetic resonance imaging have recently added to the essential diagnostic information of focal epilepsy provided by EEG.
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PMID:Development of surgical therapy of epilepsy at the Montreal Neurological Institute. 177 66

Immunocytochemical studies have identified alterations in GABA neurons in several models of seizure disorders. However, the changes have varied among different epilepsy models, and these variations presumably reflect the diversity of mechanisms that can lead to seizure disorders. In models of cortical focal epilepsy, there is strong evidence for decreases in the number of GABAergic elements, and the changes closely parallel the time course of seizure development. By contrast, in some genetic models of epilepsy, increases in the number of immunocytochemically-detectable neurons have been observed in selected brain regions. In several models of temporal lobe epilepsy, there presently is little immunocytochemical evidence for alterations of GABA neurons within the hippocampal formation despite physiological demonstrations of decreased GABA-mediated inhibition in this region. However, it remains possible that certain types of GABA neurons could be differentially affected in some seizure disorders while other types are preserved. Thus, distinguishing between different classes of GABA neurons and determining their functional roles represent major challenges for future studies of GABA neurons in seizure disorders.
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PMID:GABA neurons in seizure disorders: a review of immunocytochemical studies. 178 31

Both interictal and ictal EEG phenomena are commonly activated by functional instability. The different non-REM sleep stages comprise long-lasting periods of cyclic alternating pattern (CAP) in which arousal fluctuates between 'A phases' of greater arousal and 'B phases' of less arousal, and periods in which vigilance maintains a tonic stability (non-CAP). Previous studies have revealed that phase A induces a marked enhancement of generalized EEG paroxysms, a minor though significant activation of focal lesional bursts, but no effect on rolandic functional spikes. Conversely, phase B exerts an inhibitory modulation, especially on bilateral interictal phenomena. Because of the opposite influence of phase A and phase B also on muscle tone, we assessed the amount and distribution of nocturnal partial motor seizures in 6 subjects affected by focal epilepsy. The polysomnograms included 45 motor seizures, 43 of which occurred during non-REM sleep. Nocturnal fits were significantly more frequent in stages 1 and 3 (P less than 0.0001). Among the non-REM seizures, 42 appeared in CAP (P less than 0.0001) and always in phase A. The transient arousal and the concomitant muscle tone activation expressed by phase A of CAP is likely to support the motor components of nocturnal seizures. Sleep analysis in terms of CAP and non-CAP provides a better understanding of the continuum from subclinical EEG paroxysms to clinical manifestations and of the relations between vigilance and seizure disorders.
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PMID:Activation of partial seizures with motor signs during cyclic alternating pattern in human sleep. 181 56

In recent years, a differentiation has been made between two syndromes that are characterized by brief abnormal paroxysmal movements occurring principally at night: 1, hypnogenic paroxysmal dystonia (HPD), sometimes considered a particular form of dystonia similar to paroxysmal kinesigenic choreoathetosis, and 2, mesiofrontal epilepsy. Whether HPD is a distinct syndrome is not clear. Twenty-three patients, 11 men and 12 women, were hospitalized between 1985 and 1989 for examination of this type of abnormal paroxysmal movements (APM) occurring at night. In order to clarify the physiopathology of these abnormal nocturnal movement as focal epilepsy or a particular form of dystonia, we analyzed the personal and familial antecedents of all 23 patients, the polygraphic records during waking and sleep periods, and the results of neuroradiological examinations. Four patients were examined by positron emission tomography (PET) using i8F deoxyglucose. Symptoms first appeared between 3 and 28 years of age (M, 10.1) and developed over 1 to 20 years (M, 10.1). APM clearly occurred more commonly (greater than 90%) during sleep, usually during phases of slow-wave sleep. The sleeping patient opened his eyes and the motor signs then variously associated affective facial expression; axial postural modifications; tonic, dystonic or choreic postural movements of the limbs; pedalling; automatisms; disordered agitation and vocalization. The seizure was abruptly interrupted after 10 to 60 seconds. There was usually no postictal confusion. Thirteen patients clearly had clear epileptic antecedents: in 9, generalized tonic-clonic seizures; in 4, focal epileptic status. During nocturnal polygraphic recording, 6 patients presented a generalized seizure following a period of APM.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Postures and abnormal paroxysmal movements during sleep: hypnogenic paroxysmal dystonia or partial epilepsy?]. 190 68

Cessation of chronic (5 days), unilateral infusion of GABA into the somatomotor cortex of rats induces focal epileptic spikes which remain limited to the infused site and never evolve into generalized seizures. We have considered this finding as a new model of focal epilepsy and named it "GABA withdrawal syndrome". In the present study, we have measured local cerebral glucose utilization in order to map the cortical and subcortical regions involved in the GABA withdrawal syndrome. Local cerebral glucose utilization increased two- to three-fold in a 1-1.5 mm diameter area, involving all the cortical layers at the GABA-infusion site. This hypermetabolic area contained a central (1-2 mm diameter) hypometabolic zone showing neuronal depopulation in some animals. Except for the epileptic focus, the hemisphere ipsilateral to the infusion site was slightly hypometabolic. However, there was a large increase (three- to five-fold) in some ipsilateral thalamic nuclei (posterior oralis, ventralis postero-lateralis, centralis lateralis, ventralis lateralis and reticularis thalami nucleus). The local cerebral glucose utilization of the contralateral cortex and thalamus were unchanged. The present results confirm the focal nature of the epileptogenic syndrome produced by stopping chronic, intracortical GABA infusion. These results are markedly different from those described in the penicillin focal epilepsy model. Our data also show that specific ipsilateral thalamic relays may, by an as yet unknown mechanism, play a role in maintaining paroxysmal activity during the GABA withdrawal syndrome.
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PMID:Metabolic anatomy of the focal epilepsy produced by cessation of chronic intracortical GABA infusion in the rat. 190 65

There is abundant evidence of the close interrelation between the induction and inhibition of seizure activity and the patient's thoughts, feelings and behaviour. The detailed knowledge that we now have of the epileptic focus and the way that it is connected to the surrounding cerebral mechanisms, makes it possible for many patients with focal epilepsy to establish a significant degree of seizure control by altering their thinking and behaviour.
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PMID:Behavioural treatment of epilepsy. 211 59

Primary intraparenchymal tumors of the brain are important etiologic factors in partial or focal epilepsy. Indolent low-grade gliomas may be associated with a long-standing seizure disorder refractory to medical treatment. Surgical resection of the neoplasm and the epileptogenic area may render patients seizure-free. Removal of the tumor alone may also be associated with an excellent survival rate and surgical outcome. Conventional neurosurgical procedures are restricted in patients with tumors that are deep-seated lesions or involve functional cerebral cortex. Computer-assisted stereotactic surgical procedures have been developed for biopsy and resection of intra-axial brain-mass lesions. Stereotactic tumor resection may allow pathological determination of intracranial lesions and produce a worthwhile reduction in seizure activity in some patients with intractable partial epilepsy.
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PMID:Epilepsy and brain tumors: implications for treatment. 212 72


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