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

We developed a modern numerical approach to the multivariate linear discrimination of Fisher from 1936 based upon singular value decomposition that is sufficiently stable to permit widespread application to spatiotemporal neuronal patterns. We demonstrate this approach on an old problem in neuroscience--whether seizures have distinct dynamical states as they evolve with time. A practical result was the first demonstration that human seizures have distinct initiation and termination dynamics, an important characterization as we seek to better understand how seizures start and stop. Our approach is broadly applicable to a wide variety of neuronal data, from multichannel EEG or MEG, to sequentially acquired optical imaging data or fMRI.
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PMID:Neuronal spatiotemporal pattern discrimination: the dynamical evolution of seizures. 1619 27

The high-resolution, phased array, or surface coil techniques offer promise of improvements in diagnosis of cortical abnormalities. Further prospective studies in larger numbers of patients will be needed to determine the exact improvement, which might be expected from experienced image interpreters. Combining high-resolution imaging with MEG would seem to be the best noninvasive way of accurately localizing seizure foci, and any potential anatomic derangements, currently available to us.
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PMID:High-resolution magnetic resonance imaging (MRI), surface coil MRI, and magnetoencephalography. 1638 36

The quantification of phase synchrony between brain signals is of crucial importance for the study of large-scale interactions in the brain. Current methods are based on the estimation of the stability of the phase difference between pairs of signals over a time window, within successive frequency bands. This paper introduces a new approach to study the dynamics of brain synchronies, Frequency Flows Analysis (FFA). It allows direct tracking and characterization of the nonstationary time-frequency dynamics of phase synchrony among groups of signals. It is based on the use of the one-to-one relationship between frequency locking and phase synchrony, which applies when the concept of phase synchrony is not taken in an extended 'statistical' sense of a bias in the distribution of phase differences, but in the sense of a continuous phase difference conservation during a short period of time. In such a case, phase synchrony implies identical instantaneous frequencies among synchronized signals, with possible time varying frequencies of synchronization. In this framework, synchronous groups of signals or neural assemblies can be identified as belonging to common frequency flows, and the problem of studying synchronization becomes the problem of tracking frequency flows. We use the ridges of the analytic wavelet transforms of the signals of interest in order to estimate maps of instantaneous frequencies and reveal sustained periods of common instantaneous frequency among groups of signal. FFA is shown to track complex dynamics of synchrony in coupled oscillator models, reveal the time-frequency and spatial dynamics of synchrony convergence and divergence in epileptic seizures, and in MEG data the large-scale ongoing dynamics of synchrony correlated with conscious perception during binocular rivalry.
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PMID:Frequency flows and the time-frequency dynamics of multivariate phase synchronization in brain signals. 1641 9

Epilepsy with continuous spike- and -waves during slow-wave sleep and Landau-Kleffner syndrome are two rare childhood epilepsy syndromes. The underlying pathophysiology remains unknown. The current opinions about epidemiologic risk factors, genetic predisposition, EEG and MEG findings, influence of anti-epileptic drugs, neuroradiology, positron emission tomopgraphy, evoked potentials, auto-immunity and subpial transection are summarized.
Seizure 2006 Jun
PMID:The pathophysiological mechanisms of cognitive and behavioral disturbances in children with Landau-Kleffner syndrome or epilepsy with continuous spike-and-waves during slow-wave sleep. 1661 25

The authors assessed whether magnetoencephalography/magnetic source imaging (MEG/MSI) identified epileptogenic zones in patients with tuberous sclerosis complex (TSC). In six TSC children with focal seizures, ictal video-EEG predicted the region of resection with 56% sensitivity, 80% specificity, and 77% accuracy (p = 0.02), whereas interictal MEG/MSI fared better (100%, 94%, and 95%, respectively; p < 0.0001). Interictal MEG/MSI seems to identify epileptogenic zones more accurately in children with TSC and focal intractable epilepsy.
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PMID:Magnetic source imaging localizes epileptogenic zone in children with tuberous sclerosis complex. 1663 52

Epilepsy surgery in general is viewed with many misconceptions about its safety and efficacy, and it is an under-used modality worldwide. This deficiency is particularly relevant to children, who stand to benefit the most from early remission of seizures and elimination of the need for potentially toxic AEDs. Advancements in the field and the ability to further sway public opinion toward the established safety and efficacy of epilepsy surgery will come through less invasive techniques to map the epileptogenic zone (eg, EEG, fMRI, MEG) and reversible strategies such as neurostimulation/neuromodulation to control seizures. Two multicenter trials are underway to test the efficacy of thalamic and cortical stimulation via more sophisticated technology and devices than those available in the past.
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PMID:Surgery for epilepsy. 1672 97

Currently available digital EEG equipment provides considerably greater opportunities for clinical data analysis than is generally appreciated especially when appropriate software is used. Data from 7 different laboratories that had been obtained for routine diagnostic evaluations on 7 different EEG instruments and stored on compact disks were investigated. Since the instruments do not filter the data at input, ultra slow activity down to 0.01 Hz is currently being recorded but the attenuation factor is instrument dependent. Nevertheless, relevant clinical information is potentially available in these data and needs to be explored. Several examples in regard to epilepsy are presented. Determination of seizure onset may depend on the frequencies that are examined. The use of appropriate filter settings and viewing windows for the clinical question to be answered is stressed. Differentiation between simple and complex spike wave discharges, as well as spread of spikes, can readily be achieved by expanding the time base to 1 or 2 seconds and placing a cursor on the peak of the negative spike. Latencies in the millisecond range can then become apparent. EEGs co-registered with MEG should be evaluated with the same software in order to allow an adequate assessment of the similarities and differences between electrical and magnetic activity. An example of a comparison of EEG, planar gradiometers and magnetometers for an averaged spike is shown.
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PMID:Optimal evaluation of digital electroencephalograms. 1692 1

Optical topography is a new alternative for noninvasive functional brain mapping. It uses near infrared light projected from the scalp into the brain. The reflected light which is sampled 30 mm apart from the injection probe carries the information of hemoglobin concentration change of the regional brain tissue lying at the midpoint of probes. When mapped using 24 channels, we see the real time brain activities during various tasks allowing the head movements as well. It is utilized in measuring the language function, and diagnosis of epilepsy focus. Several such clinical applications are demonstrated. The brain activities are measured during finger tapping. The mapping during word generation task shows the activities of Broca's area indicating the hemispheric dominancy of language function. We correlated the results between optical topography measurement and amytal test, showing 85% matching according to the language dominancy. It also useful in identifying the epilepsy focus because the hemoglobin increases at the focus region in the initial phase of epileptic seizures. In our study, the feasibility of optical topography in focus diagnosis is confirmed in 85% of 27 cases. The advantages of optical topography are as follows. 1: It is portable to various clinical scenes including patient ward and outpatient clinic. 2: It can be used conjunction with fMRI and MEG. 3: It measures the brain activities even during the head movements.
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PMID:[Applications of optical topography in neurosurgery]. 1753 71

Considering the brain as a complex network of interacting dynamical systems offers new insights into higher level brain processes such as memory, planning, and abstract reasoning as well as various types of brain pathophysiology. This viewpoint provides the opportunity to apply new insights in network sciences, such as the discovery of small world and scale free networks, to data on anatomical and functional connectivity in the brain. In this review we start with some background knowledge on the history and recent advances in network theories in general. We emphasize the correlation between the structural properties of networks and the dynamics of these networks. We subsequently demonstrate through evidence from computational studies, in vivo experiments, and functional MRI, EEG and MEG studies in humans, that both the functional and anatomical connectivity of the healthy brain have many features of a small world network, but only to a limited extent of a scale free network. The small world structure of neural networks is hypothesized to reflect an optimal configuration associated with rapid synchronization and information transfer, minimal wiring costs, resilience to certain types of damage, as well as a balance between local processing and global integration. Eventually, we review the current knowledge on the effects of focal and diffuse brain disease on neural network characteristics, and demonstrate increasing evidence that both cognitive and psychiatric disturbances, as well as risk of epileptic seizures, are correlated with (changes in) functional network architectural features.
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PMID:The application of graph theoretical analysis to complex networks in the brain. 1790 Sep 77

Near-infrared spectroscopy (NIRS) is a novel imaging technique of potential value in the pre-surgical investigation of patients with refractory epilepsy. We recorded simultaneously electrophysiology (EEG; Compumedics, USA) and near-infrared spectroscopy (NIRS; ISS, USA) to examine the localization of the ictal onset zone and assess language lateralization in a young epileptic boy (L.H., 10 years) as part of his pre-surgical evaluation. L.H. underwent a prolonged EEG-NIRS recording while electro-clinical and electrical seizures were recorded. Results were compared to those obtained with other pre-surgical techniques (SPECT, FDG-PET, EEG-fMRI and EEG-MEG) and showed good concordance for ictal onset zone localization. A second NIRS session without EEG was carried out in order to investigate language lateralization. For this purpose, the patient performed a categorical verbal-fluency task during NIRS recordings. Results showed left-hemisphere dominance for language function in this young boy. This case report illustrates that multi-channel EEG-NIRS has the potential to contribute favourably to pre-surgical investigation in young patients.
Seizure 2008 Sep
PMID:Non-invasive pre-surgical investigation of a 10 year-old epileptic boy using simultaneous EEG-NIRS. 1837 8


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