Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0036572 (seizures)
 80,221 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We investigated the localization of current sources in the time and frequency domain from spontaneous MEG data recorded from nine epileptic patients (six females; three males) randomly selected, who had a mean age of 41 years old (range of 17-78 years old), with different types of epilepsy. The MEG data were recorded in a magnetically shielded room with a whole-head 122 channel biomagnetometer. For each MEG spike, we calculated the single Equivalent Current Dipole (ECD) sources at the initial spike peaks with a spherical model. MRI and EEG findings were available in patients' records. Prominent low frequencies can be seen in the majority of channels. For each patient there was an increase of the frequency range after the ECD in comparison with the frequency range before the ECD, in the whole study group due to epileptic discharge which is statistically significant (p=0.02). There was also a statistical significant difference in the increase of the frequency range in four patients with pathologic MRI (p=0.05), in five patients with normal MRI (p=0.02), in five patients with a high incidence of seizures (p=0.04) and in four patients with onset<10 years (p=0.04). The MEG analysis of neuromagnetic data gives information about the modification of the frequency range in the epileptic brains.
 ...
PMID:Meg evaluation of epileptic activity in the time and frequency domain. 1913 96

According to the international classification of epileptic seizures (1981) generalized seizures present ictal signs indicating seizure onset in both hemispheres whereas focal seizures present ictal signs pointing to one hemisphere at seizure onset. Recent neurophysiological studies using MEG, EEG, and fMRI suggest that in case of idiopathic generalized absence epilepsies, activity predominates in specific networks, which include frontoparietal cortical as well as subcortical areas of both hemispheres. In these network regions, epileptic activity can occur circumscribed and focal as spike or spike-wave activity but also widely distributed, bilateral, and homologous. As a consequence to the classification of "generalized" epileptic seizures and syndromes, it might be possible to distinguish a subgroup: regional bilateral homologous epilepsies. These must be distinguished from a pure culture of focal frontal lobe epilepsies, which can also be accompanied by the lead symptom of absences.
 ...
PMID:[Current clinical-neurophysiological findings in absence epilepsies]. 1932 56

Seven patients with idiopathic generalized epilepsies were investigated using MEG and EEG. Spike-wave series were seen in all patients, single spikes in six. For both, source analysis showed most often involvement of frontal, perinsular and subcortical/thalamic areas. In all patients, a unilateral frontal accentuation of activity could be observed. Patients with juvenile myoclonic and myoclonic absence epilepsy presented with localizations mainly in the central and premotor regions versus prefrontal accentuation in the other absence patients. MEG/EEG source localization provides important information concerning regional network involvement in idiopathic generalized epilepsies. As a consequence for a neurophysiological concept of "generalized" epileptic seizures and syndromes, a third subgroup with regional activity in bilateral homologous regions can be differentiated next to pure focal and multifocal generalized epilepsies.
 ...
PMID:Network characteristics of idiopathic generalized epilepsies in combined MEG/EEG. 1939 98

Malformations of cortical development (MCD) include a broad range of disorders that result from disruption of the major steps of cortical development: cell proliferation in germinal zones, neuronal migration and cortical organization. With the improvement and increased utilization of modern imaging techniques, MCD have been increasingly recognized as a major cause of seizure disorders. The advent of Magnetic Resonance Imaging (MRI), in particular, has revolutionized the investigation and the treatment of patients with epilepsy. High-resolution MRI may elucidate the type, the extension and the localization of MCD; therefore, in a group of patients suffering from drug-resistant partial epilepsy (DRPE), MRI greatly contributes to the identification of subjects who are suitable for surgical treatment. In the recent past, many efforts were addressed to establish the MRI diagnostic criteria for a peculiar group of MCD, namely focal cortical dysplasias (FCD), histopathologically distinguished as types I and II. Some subtle FCD, which were previously cryptic to imaging investigation, can now be recognized by MRI, however their detection and specification remains challenging. This review will re-visit the neuroimaging findings, including structural MRI, PET, co-registered PET/MRI, MEG and diffusion tensor imaging (DTI) of FCD types I and II. Three major issues will be discussed: 1) the morphological MRI features of the FCDs, 2) the utility of PET and MEG and the use of co-registration methods and 3) diffusion tensor imaging (DTI) as a future modality of investigation, which may add additional informations regarding the microstructure of the grey matter (GM) and white matter (WM) in cortical dysplasia.
 ...
PMID:Imaging of malformations of cortical development. 1972 May 83

Persistent Genital Arousal Disorder (PGAD) refers to the experience of persistent sensations of genital arousal that are felt to be unprovoked, intrusive and unrelieved by one or several orgasms. It is often mistaken for hypersexuality since PGAD often results in a high frequency of sexual behaviour. At present little is known with certainty about the etiology of this condition. We described a woman with typical PGAD symptoms and orgasmic seizures that we found to be related to a specific epileptic focus. We performed a EEG/MEG and fMRI spontaneous activity study during genital arousal symptoms and after the chronic administration of 300 mg/day of topiramate. From MEG data an epileptic focus was localized in the left posterior insular gyrus (LPIG). FMRI data evidenced that sexual excitation symptoms with PGAD could be correlated with an increased functional connectivity (FC) between different brain areas: LPIG (epileptic focus), left middle frontal gyrus, left inferior and superior temporal gyrus and left inferior parietal lobe. The reduction of the FC observed after antiepileptic therapy was more marked in the left than in the right hemisphere in agreement with the lateralization identified by MEG results. Treatment completely abolished PGAD symptoms and functional hyperconnectivity. The functional hyperconnectivity found in the neuronal network including the epileptic focus could suggest a possible central mechanism for PGAD.
 ...
PMID:Persistent genital arousal disorder associated with functional hyperconnectivity of an epileptic focus. 2014 94

We describe a 42-year old patient with right hand sensorimotor seizures who underwent extraoperative cortical stimulation mapping (CSM) of the left primary motor cortex (M1). Cortical stimulation of the region where primary motor cortex was expected evoked exclusively complex motor responses with proximal right arm and proximal left leg asymmetric tonic movements that are usually observed on stimulation of the supplementary motor area (SMA). Right hand function could not be isolated during either extraoperative or intraoperative cortical stimulation of the anatomical M1 representation. Ictal and interictal activity was contained within the region with the abnormal motor response, and MEG of interictal activity showed spike propagation from the left mesial to lateral frontal cortex. This propagation pathway may have facilitated M1-to-SMA connectivity and therefore explain the unusual motor response after stimulation of M1. This case highlights the potential impact of interictal activity on plasticity of the motor cortex.
 ...
PMID:Unusual cortical stimulation findings: connectivity between primary motor and supplementary motor areas. 2094 36

Gelastic seizure is an uncommon type of seizure which is characterized by recurrent bouts of unprovoked and stereotyped laughter. It is commonly observed in patients with hypothalamic hamartoma, while its association with other cerebral lesions is rare. The patient was a 15-year-old right-handed male. His chief complaints were recurrent onsets of laughter and unconsciousness for 10 years. On average, he had several to dozens of onsets per day and had failed most antiepileptic medications before admission. Presurgical evaluation included MRI, video-EEG, MEG and subdural electrode EEG. The results of MEG and subdural electrode EEG suggested that the epileptogenic focus was located on the lateral surface of the right frontal lobe, chiefly on the anterior part of the inferior frontal gyrus. The focus was removed under intraoperative ECoG monitoring which was consistent with the results of MEG and subdural electrode EEG. Histopathology revealed focal cortical dysplasia with balloon cells (type II). The patient kept seizure-free during the short-term follow up of 3 months. In the past literature, the medial frontal and basal temporal lobes, besides the hypothalamus, were thought to play major roles in the case of gelastic seizure. Our results suggest that the lateral surface of the frontal lobe might also be one part of the epileptogenic network in gelastic seizures. Removal of the epileptogenic focus under thorough pre-surgical evaluation might result in good seizure control in patients with gelastic seizures.
Seizure 2011 May
PMID:Surgical outcome of gelastic epilepsy of frontal lobe origin: a case report. 2120 13

Auditory vocal hallucinations are sometimes observed in temporal-lobe epilepsy, but are a frequent sign of psychosis and may rarely be mistaken for the latter. Here we report two patients who suffered from auditory vocal hallucinations, described as unintelligible human voices perceived at their left side during epileptic seizures. MEG revealed interictal epileptic discharges within the anterior partition of the right superior temporal gyrus; signal-to-noise ratio of these discharges was overall poor in EEG. The findings suggest that auditory vocal hallucinations without verbal content can evolve in the right hemisphere and are probably independent of language lateralization. This is in accordance with evidence from functional imaging, whereas most previous reports of seizures with auditory vocal hallucinations were confined to the left hemisphere.
 ...
PMID:Voices behind the left shoulder: two patients with right-sided temporal lobe epilepsy. 2147 50

To describe the spatial and temporal profiles of connectivity networks and sources preceding generalized spike-and-wave discharges (SWDs) in human absence epilepsy. Nonlinear associations of MEG signals and cluster indices obtained within the framework of graph theory were determined, while source localization in the frequency domain was performed in the low frequency bands with dynamic imaging of coherent sources. The results were projected on a three-dimensional surface rendering of the brain using a semi-realistic head model and MRI images obtained for each of the five patients studied. An increase in clustering and a decrease in path length preceding SWD onset and a rhythmic pattern of increasing and decreasing connectivity were seen during SWDs. Beamforming showed a consistent appearance of a low frequency frontal cortical source prior to the first generalized spikes. This source was preceded by a low frequency occipital source. The changes in the connectivity networks with the onset of SWDs suggest a pathologically predisposed state towards synchronous seizure networks with increasing connectivity from interictal to preictal and ictal state, while the occipital and frontal low frequency early preictal sources demonstrate that SWDs are not suddenly arising but gradually build up in a dynamic network.
 ...
PMID:Space-time network connectivity and cortical activations preceding spike wave discharges in human absence epilepsy: a MEG study. 2153 20

Photosensitive epilepsy (PSE) offers a highly reproducible model to investigate whether changes in neuronal activity preceding the transition to an epileptic photoparoxysmal response (PPR) may be detected. We investigated this possibility in patients with idiopathic PSE using MEG, as well as normal controls and non-photosensitive epileptic patients of the same age group. Spectral analysis of the MEG signals recorded during intermittent light stimulation revealed relevant information in the phase spectrum. To quantify this effect, we introduced a second order response feature of the stimulus-triggered visual response preceding the PPR: the phase clustering index, which measures how close the phases of successive periods are grouped for each frequency component for all periods of the stimuli applied. We found that an enhancement of phase synchrony in the gamma-band (30-120Hz), harmonically related to the frequency of stimulation, preceded the stimulation trials that evolved into PPRs, and differed significantly from that encountered in trials not followed by PPR or in control subjects. Thus this index can be considered a valuable index of the pro-ictal transition to seizures in photosensitive epilepsy.
 ...
PMID:Transition to seizure in photosensitive epilepsy. 2207 50


<< Previous 1 2 3 4 5 6 7 8 Next >>