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

Visual potentials evoked by pattern reversal (PRVEPs) were studied in 64 normal subjects (age range 7 to 15 years) and in 15 patients with primary generalized epilepsy (age range 8 to 13 years), 10 of whom were without anticonvulsant medication. Most of them were studied during sodium valproate (VPR) therapy and some during carbamazepine (CBZ) medication. A Quadristim set (Alvar) was used to present checkerboard patterns on a TV monitor, to amplify the EEG signals and to average and plot the evoked potentials. The potentials were elicited by binocular full-field 2/s checkerboard reversals, recorded from an electrode 4 cm above the inion, and analyzed for latency, amplitude and waveform. Our PRVEP measurements examined peak latency of positive P2 (or P100) component and trough-to-peak amplitude on N1P2 wave complex. The degree of similarity between pairs of PRVEP plots were determined by Pearson correlation coefficient r for an analysis time of 150 ms. In most of our patients, no pronounced influence of the disease itself on the parameters and waveform of the normal PRVEP pattern was demonstrated if anticonvulsant drugs were not taken. In patients who were under complete seizure control, the anticonvulsant did not change the PRVEP morphology as well. The PRVEP abnormality was most pronounced in patients who were taking anticonvulsant medication, but whose seizures were poorly controlled. This pattern distortion can be revealed by the correlation coefficient, but not by other PRVEP parameters. Therefore, this coefficient may be useful as a sensitive and objective measure both of PRVEP distortion and PRVEP improvement. Our results give further evidence that nondemyelinating disorders, but with synaptic transmission defects, can produce measurable changes in PRVEP morphology.
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PMID:Pattern-reversal visual evoked potentials recorded in children with generalized epilepsy. 222 73

Visual (V), somatosensory (S) and brainstem auditory (BA) evoked potentials (EPs) were determined in 22 epileptic patients, mostly with partial seizures, who received add-on treatment with vigabatrin (1-3 g/day, stratified according to body weight) and placebo, each given for 7 weeks according to a double-blind, randomized cross-over design. At pretreatment assessment, BAEPs and SEPs were found to be within normal limits in most of the patients tested, while for VEPs several abnormal responses were found, including a marked prolongation of P100 latency values in the majority of cases. None of the EP parameters examined was significantly influenced by vigabatrin treatment. These results support the evidence that enhancement of GABA-ergic transmission does not substantially affect the functional state of afferent sensory pathways as assessed by EP analysis. The significance of these findings with respect to the safety of vigabatrin therapy is discussed.
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PMID:Effect of vigabatrin (gamma-vinyl-GABA) on visual, brainstem auditory and somatosensory evoked potentials in epileptic patients. 313 Feb 53

We have studied a patient (pt) in status epilepticus with visual seizures (szs) arising focally from the right occipital area and have recorded the visual evoked potential (VEP) to three different stimuli under three different conditions (during, between and with no szs). The pt experienced "sparkling" in the contralateral visual field as the sz and the intensity of the "sparkling" was directly related to the frequency of the ictal activity recorded on the EEG. During the szs the VEPs could still be recorded, but the amplitude of the P100 was higher on the contralateral side with pattern reversal (PR) stimuli, and with flashes (FL) the positive peak after the P100 was less evident on the ipsilateral side. Latencies to these latter two positivities were generally shorter than in normals, with much greater standard deviations ipsilaterally with FL and contralaterally with PR, especially during the actual szs. The relationship between VEP generation and visual sz phenomena is discussed.
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PMID:The relationship between visual seizures and visual evoked potentials. 409 66

The effect of seizures on subsequent long-term behavior was studied in immature rats. A similar severity of seizures were induced in 20-day old rats (P20) and 45-day old rats (P45) by intraperitoneal injections of pilocarpine at doses of 200 mg/kg and 380 mg/kg, respectively. Immediately after injection of pilocarpine, prolonged seizures with electroencephalographic ictal discharges were observed in both groups of rats. These seizures were followed by seemingly complete neurological recovery. In rats that received pilocarpine at P45 spontaneous recurrent seizures appeared after 4-10 days and persisted until completion of the study at P100. Behavioral tests performed when the rats were fully mature demonstrated that they were more aggressive when handled, more active in open field, and had deficits in learning platform position in the water maze as compared to controls. Furthermore, flurothyl seizure latency was significantly lower in pilocarpine-treated P45 rats than controls. Histology examination showed gross cell loss in the CA3 subfield of the hippocampus in four out of six pilocarpine-treated rats while no cell loss was found in control rats. Rats that received pilocarpine at P20, despite having more severe seizures than the P45 rats, had no histological lesions, did not develop spontaneous recurrent seizures, and had no significant difference in the flurothyl seizure latency test when compared to their controls. While there was no difference between the control and pilocarpine-treated rats in the handling and open field test, P20 rats receiving pilocarpine were slower in learning platform position in the water maze than the controls. Rats receiving pilocarpine at P45 performed significantly more poorly than rats treated at P20 in the water maze. These results suggest that prolonged seizures in immature rats can cause long-term behavioral deficits. However, the severity and nature of these deficits are highly age dependent.
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PMID:Long-term behavioral deficits following pilocarpine seizures in immature rats. 769 95

The present study evaluated pattern shift visual evoked potential (VEP) amplitudes and latencies in four groups of adult subjects, characterized by the presence/absence of a recent history of alcohol dependence factorially crossed with the presence/absence of a recent history of cocaine dependence. All of the subjects were healthy and uncomplicated by histories of serious head injury, seizures (including drug-related seizures), and major medical, neurological, or psychiatric disorders. The subjects comprising the three patient groups were evaluated after 1 - 5 months of verified abstinence. Analyses of VEPs evoked by checkerboard reversal indicated a main effect of previous cocaine dependence on P100 latency. No main effect of previous alcohol dependence and no alcohol by cocaine dependence interaction were detected. The increased P100 latencies detected in abstinent, cocaine-dependent subjects are most likely related to cerebrovascular and neurological effects of chronic cocaine use.
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PMID:Pattern shift visual evoked potentials in abstinent cocaine-dependent, alcohol-dependent, and cross-dependent patients. 886 98

Pattern-reversal visual evoked potentials (VEPs) were recorded in 64 patients with newly diagnosed epilepsy. Before starting medication the patients with partial and primary generalized epilepsy, had prolonged latencies of the VEPs component P100, as compared with controls. VEPs were repeated after 3 months in 43 patients with focal epilepsy, during carbamazepine (22 cases) or phenytoin (21 cases) treatment. The plasma concentration of the drugs were within therapeutic levels. Carbamazepine but not phenytoin, was associated with prolongation of the P100 peak latency and induced increase of its amplitude, as compared with the baseline condition. The VEPs abnormality was most pronounced in patients whose seizures were poorly controlled. We conclude, that administration of carbamazepine or phenytoin, at therapeutic serum level, have minimal effect on the VEPs.
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PMID:[Effect of phenytoin and carbamazepine on evoked potentials in patients with newly diagnosed epilepsy. Part I. Visual evoked potentials]. 917 34

The measurement of evoked potentials (EPs) may be particularly useful in clinical neuropharmacology for investigation of drug effects of afferent nerve conduction within CNS. The study aims at estimating the long term effects of conventional or slow release formulation (CR) of carbamazepine (CBZ) and valproid acid (VPA) on visual (VPA) and brainstem auditory (BAEP) evoked potentials. Investigation covered 125 patients 8 to 18 years old to whom both formulations of CBZ or VPA were administered in monotherapy. Everyone received a drug dosage which gave an adequate therapeutic plasma concentration and satisfactory seizure control. Antiepileptic drugs (AEDs) plasma levels were measured by means of fluorescence polarization immunoassay method aided of TDx Analyzer (Abbott, Diagnostic). EPs were registered by means of Multiliner (Toennies, Germany). A pattern of reversal stimulation for VEP was used. The latencies of N75, P100, N145 as well as interpeak amplitudes of N75/P100, P100/N145 were evaluated. The following BAEP parameters were considered: morphology of the potential, absolute latencies of waves I, III, V and I-III, III-V, I-V. EP were always performed in the same conditions and with the same equipment for the epileptic and control groups. The obtained values were compared with age-matched control group. The following BAEP abnormalities were observed: prolonged absolute latencies of waves I, III, V as well as prolonged IPLs I-III. The BAEP V/I amplitude ratio and morphology of the waves were normal in all patients. The VEPs abnormalities manifested as prolongation of P100 or N145 latencies and reduction of amplitudes N75/P100, P100/N145. Results of these electrophysiological studies with CBZ and VPA demonstrate that EP are sensitive, noninvasive reflectors of AEDs effects within the CNS.
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PMID:[Bimodal evoked potentials during long-term therapy with conventional or slow release preparations of carbamazepine and valproic acid in children and adolescents with epilepsy]. 1076 52

As some apparently idiopatic epilepsies may occasionally pose diagnostic difficulties in regard to their precise status of etiology, evoked potentials, particularly visual evoked potential (VEP), may contribute to the diagnosis of childhood epilepsy with occipital paroxysms (CEOP) as a subsidiary method of evaluation. This study includes 19 children (10 boys 52.6%; 9 girls 47.4%) ranging in age from 5 to 17 years (mean SD = 9.68 3.28) suffering from CEOP and a control group of 30 normal children, matched for chronological age and sex. Peak amplitudes and latencies of the P100 component for pattern-shift VEP (PVEP) and of major positivity for flash VEP (FVEP) are measured, respectively. The results from this study demonstrate that amplitude and latency values in patients with CEOP differs insignificantly when compared with controls. Although, non-significantly, mean values of amplitudes for both PVEP and FVEP were higher in the patients than in the normal children, whereas latencies in FVEP were somewhat longer. There may be some tendency for the amplitudes to increase and the latencies to be delayed in VEPs in patients with CEOP, when an overall interpretation of our and similar studies are considered. In certain cases of diagnostic difficulty, VEP values may provide further information for the clinician, regarding either a symptomatic or an idiopathic nature of the underlying disorder.
Seizure 2000 Jun
PMID:A study on visual evoked responses in childhood epilepsy with occipital paroxysms. 1088 Feb 87

Brain plasticity refers to its ability to recover after damage. Visual field plasticity is not well recognized. We report a 12-year-old female who first presented with recurrent seizures and was subsequently found to have a large, right occipital cortical dysplasia on magnetic resonance imaging. Her visual field by Goldmann perimetry was totally normal. Visual-evoked potential studies revealed the left hemifield P100 response was detected maximally at the right temporal and parietal regions. A weak but reproducible right hemifield P100 response was located at the right medial skull base. Functional magnetic resonance imaging with flashlight stimulation revealed cerebral activity mainly at the right posterior temporal and parietal lobes and left occipital lobe. These studies suggested that the left hemifield function was located at the right posterior temporal and parietal lobes. The left occipital lobe may also have been reorganized, with a P100 vector pointing out from its inferiomedial base. We reviewed other related reported cases. We believe that visual-evoked potential studies and visual functional magnetic resonance imaging should be performed more liberally for recognition of visual field plasticity.
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PMID:Visual field plasticity in a female with right occipital cortical dysplasia. 1103 90

Adenosine is an endogenous modulator that has an inhibitory effect on neuronal activity. The aim of this work was to investigate the role of aminophylline, an adenosine receptor antagonist, on the long-term effects of status epilepticus (SE) in the developing brain. Four groups of rats at the postnatal age of 12 days were intraperitoneally administered with saline, aminophylline (50 mg/kg), lithium-pilocarpine (Li-PC) (3 mEq/kg-60 mg/kg), and Li-PC plus aminophylline, respectively. The four groups were tested for spatial memory using the Morris water maze task at P80 and motor performance by the Rotarod test at P100. The brains were then analyzed with cresyl violet stain for histological lesions and evaluated for mossy fiber sprouting with the Timm stain. At the acute stage, all rats subjected to Li-PC developed SE and no seizures were elicited in the saline-treated or aminophylline-treated rats. The seizure duration was longer in the Li-PC plus aminophylline group (346.9+/-32.7 min) as compared with that in the Li-PC group (265.2+/-9.8 min). The difference of mortality was not significant. Rats without seizures exhibited no motor imbalance, spatial deficits, or morphological changes. The rats with Li-PC-induced SE demonstrated spatial memory deficits without motor incoordination or morphological changes. However, the rats subjected to Li-PC plus aminophylline exhibited motor impairment and morphological changes, including neuronal cell loss in CA1 area and increased mossy fiber sprouting in CA3 area. In addition, the rats of Li-PC plus aminophylline had greater spatial memory deficits than that seen in rats with Li-PC. We concluded that an adenosine receptor antagonist, such as aminophylline, had synergistic effects on the SE-induced long-term deficit of cognition and motor performance in the developing brain. The present study may provide experimental evidence and lead to novel therapeutic interventions.
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PMID:Aminophylline exacerbates status epilepticus-induced neuronal damages in immature rats: a morphological, motor and behavioral study. 1207 43


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